e/f IA. WATER AND WATER SUPPLIES WATEE AND WATEE SUPPLIES JOHN C. THEESH, \\ D.SC. (LONDON); M.D. (VICTORIA); D.P.H. (CAMBRIDGE); MEDICAL OFFICER OF HEALTH TO THE ESSEX COUNTY COUNCIL. LECTURER ON " PUBLIC HEALTH," KING'S COLLEGE, LONDON. EDITOR OF THE "JOURNAL OF STATE MBDICINE." HON. SEC. INCORPOR- ATED SOCIETY MEDICAL OFFICERS OF HEALTH. FELLOW OF THE INSTITUTE OF CHEMISTRY. MEMBER OF THE SOCIETY OF PUBLIC ANALYSTS, ETC. SECOND REVISED EDITION. PHILADELPHIA: P. BLAKLSTON'S SON & CO., 1012 WALNUT STREET. 1900. Printed in England. Entered at Stationers' Hall. PREFACE IT is now fully recognised that an abundant supply of pure water is an absolute necessity for the preserva- tion of health, and that one of the chief duties of all Sanitary Authorities is to see that all the inhabitants of their districts have, within a reasonable distance, an available supply of wholesome water wherever such can be obtained at a reasonable cost. The main object of this little work is to place within the reach of all persons interested in public health the information requisite for forming an opinion as to whether any supply or proposed supply is sufficiently wholesome and abundant, and whether the cost can be considered reasonable. It does not pretend to be a treatise on Engineer- ing, yet it is hoped that it contains sufficient detail to enable any one who has studied it to consider in- telligently any scheme which may be submitted for supplying a community with water, whether that community be large or small. Whilst all our large towns have obtained more or less satisfactory supplies of water for their inhabitants, the great bulk of the population living in villages and rural districts generally is still dependent upon im- properly constructed and unprotected shallow wells, vi WATER SUPPLIES or even upon more questionable sources for its supply. The cause is not far to seek. Neither the Sanitary Authorities nor the rural populations are as yet fully alive to the importance of a good water supply, and have no knowledge of how to set about remedying the present conditions even if regarded as unsatis- factory. There is also a widespread and generally erroneous impression that scattered populations cannot be supplied with water from sources at a distance at a reasonable cost. To prove the fallacy of this im- pression particulars are given of a few typical schemes which have been successfully carried out in thinly- populated districts, and it is hoped that the example set by these enterprising authorities will be widely followed. The supply of water to rural districts is a question which has engrossed the attention of Medical Officers of Health ever since such officials were appointed, but too often they have been satisfied with merely reporting that water supplies were un- satisfactory. Such reports are not sufficient to over- come the apathy of Sanitary Authorities or to arouse any great interest in the subject in the districts concerned. The Medical Officer must not only prove that the present supplies are inadequate in quantity or unwholesome in quality, or both, but in conjunction with the Surveyor he must be prepared to formulate a scheme and to prove that it is practi- cable. To enable him to do this is one of the objects of this work. The practical experience gained in large rural districts in which it has been my privilege to submit such schemes and see them carried to a success- ful completion, is embodied in various chapters, and PREFA CE vn I hope will prove of value to all who are interested in the well-being of our rural populations. A brief rtsumt of the law relating to water supplies is given in the final chapter, and I have to thank my friend, A. Freeman, Esq., Clerk to the Maldon Rural District Council, for many suggestions, and for revising everything therein relating to the law. All schemes for establishing public water supplies in districts hitherto dependent upon water from ques- tionable sources are certain to meet with considerable opposition, but District Councils and their officers may take heart from the experience of others. Carry out the work satisfactorily, and those who were loudest in opposition will ere long frankly acknowledge the value of the boon conferred. JOHN C. THRESH. CHELMSFORD, January 1896. CONTENTS CHAPTER I WATER, ITS COMPOSITION, PROPERTIES, ETC. Composition of water Pure water not found in nature Effect of temperature Maximum density Latent heat Expansion during act of freezing Boiling point influenced by atmospheric pressure Evaporation of water, snow, and ice Solvent powers Common constituents of natural waters Hardness Action on metals Lead poisoning Hygienically pure water Mineral waters Portable waters, classification of. . . . . . Pages 1-11 CHAPTER II RAIN AND EAIN WATER Distillation Moisture contained in the atmosphere Evaporation, from the ocean, from land surfaces, etc. The causes of rain Rainfall, by what influenced, how determined Constituents of rain water, effect of proximity to ocean, towns, etc. Pollution during collection and storage Amount available from roofs, and specially prepared surfaces Rain-water separators Storage for domestic purposes Rainfall source of all water supplies Natural waters in order of purity Composition of rain water Pages 12-27 CHAPTER III SURFACE WATER Characteristics of, from various geological formations Effect of soil and cultivation of ground surface Ponds, lakes, and reservoirs Lakes as natural reservoirs, Loch Katrine, Lake Vyrnwy, Thirlmere Aberystwith water supply Glasgow water supply Analyses of upland surface waters Analyses of public water supplies derived from uplands and moorlands .... Pages 28-40 x WATER SUPPLIES CHAPTER IV SUBSOIL WATER Bogs, marshes, and swamps Pervious and non-pervious subsoils "Pockets" of gravel Permeability, imbibition, and saturation of rock Variation in level of subsoil water and the causes thereof Amount of water held by various rocks Movement of subsoil water Proportion of rainfall which percolates into subsoil Water, how obtainable from subsoil Quantity obtainable, how ascertained Shallow- well water Subterranean rivers Budapest and Perth examples of towns supplied from subsoil Quality of subsoil water How 7 polluted Koch on "subsoil water " Towns in Massachusetts supplied with subsoil water Effect of towns, villages, etc., on subsoil water Example, village of Writtle, Essex Analyses of shallow-well waters from various geological sources Analyses of public and other supplies derived from subsoil . . . . . . . Pages 41-54 CHAPTER V NATURAL SPRING WATER Perennial, intermittent, and variable springs Origin of springs Cold hot, ascending and descending springs Artificial springs The natural springs of Clifton, Batii, Buxton, Matlock, and Chelten- ham Springs, how? gauged Causes of variation in flow Dr. Whitaker on the King's Lynn water supply Bristol supplied from springs Utilisation of springs Character of spring water from various geological sources Analyses of spring waters Pages 55-69 CHAPTER VI DEEP-WELL WATERS Difference between "shallow" and "deep" wells Artesian wells- Subterranean reservoirs or rivers Source of deep -well water- Chief water-bearing strata Supply obtainable from deep wells, how affected : by extent and character of outcrop, average rainfall, continuity of water-bearing strata, selection of site Advantages of underground water supplies Effect of proximity to other wells Supply to Long Eaton, Castle Donington, and Melbourne Supply of deep-well water for the City of London Report of Royal Commission on metropolitan water supply Deep wells in the Colonies, United States Recent analyses of deep-well waters Pages 70-85 CONTENTS xi CHAPTER VII RIVER WATER Catchment basins Drainage areas Effects of towns, villages, manu- factories, etc. , within a drainage area Self-purification of rivers The Seine, Thames, Tees, etc. Flow of streams Amount of water available, factors influencing Maximum, minimum, and mean rainfall Seasonal variation of rainfall, effects of Portion of rainfall reaching rivers Stream gaugings, different methods of Towns deriving their water supplies from rivers Pages 86-103 CHAPTER VIII QUALITY OF DRINKING WATERS Colour of pure and impure waters Taste and odour, by what in- fluenced Effect of mineral, animal, and vegetable impurities Turbidity, to what due Organisms found in water Soluble con- stituents of potable waters, inorganic and organic -What con- stitutes a good potable water ... . . Pages 104-121 CHAPTER IX IMPURE WATER AND ITS EFFECT UPON HEALTH Constituents which may cause diarrhoea Diseases caused by mineral constituents : goitre, diarrhoea, plumbism, etc. Diseases due to specific organisms : malaria, enteric or typhoid fever, cholera, yellow fever, oriental boils, Zoo - parasitic diseases : Bilharzia, /uuniatobia, Filaria sangtiinis, Filaria dracunculus, etc. Diseases of animals caused by impure water . . . Pages 122-159 CHAPTER X THE INTERPRETATION OF WATER ANALYSES The inorganic, organic, and bacterial constituents, relative importance of Erroneous conclusions may be drawn from both chemical and bacteriological analyses Significance of chlorides, nitrates and nitrites, ammonia, phosphates, organic matter Albumenoid ammonia Organic carbon and oxygen Oxygen absorbed Sir Charles Cameron on the value of chemical analyses Intermittent pollution Variation in quality of water from one and the same source Table of analyses, showing bow little dependence can be xii WATER SUPPLIES placed upon the results of a chemical analysis Remarks on the waters referred to in the Table of Analyses The bacteriological examination of water Microbes found in water and their signifi- cance Standard of purity, absurdity of Importance of the examination of the source of the water . . Pages 160-192 CHAPTER XI THE POLLUTION OF DRINKING WATER Pollution at its source Surface and river waters Subsoil water Deep- well water Pollution arising during storage Pollution during distribution Pages 193-214 CHAPTER XII THE SELF-PURIFICATION OF RIVERS Rivers, how polluted Natural purification Oxidation, sedimentation, effect of sunlight, organisms, etc. Can a sewage-polluted river water ever be rendered perfectly safe for a public water supply ? Pages 215-224 CHAPTER XIII THE PURIFICATION OF WATER ON THE LARGE SCALE Sedimentation Filtration, efficiency of, how determined Dr. P. Frankland's experiments at the London Waterworks Table showing effect of subsidence Experiments conducted by the Massachusetts State Board of Health Effects of (a) rapidity of filtration, (b) thickness of filtering media, (c) fineness of filtering media, (d) scraping the surface of filter, etc. Conclusions based upon Massachusetts experiments Dr. Koch on the "conditions necessary for efficient filtration" The Altona Waterworks- Action of sand Construction of filter beds Size and number of beds required Table showing area of filter and rate of filtration at different works Natural filtration Filter galleries Atkins' scrubbers American filtering machines Polarite, spongy iron, magnetic carbide, and other filtering materials ; where used ; efficiency of Sand washing " Softening " purifies water Pages 225-246 CHAPTER XIV DOMESTIC PURIFICATION Low-pressure filters High-pressure filters Table filters Cottage filter Efficiency of filters Distillation Aeration Purification by the addition of chemicals .... Pages 247-255 CONTENTS xiii CHAPTER XV THE SOFTENING OF HARD WATER Softening by boiling; by addition of chemicals Clark's lime process Atkins' process Southampton Waterworks The "Porter-Clark " process The Stanhope water softener The Howatson "Softener " Stroud Waterworks Cost of various processes Saving effected by using soft water in houses, institutions, and towns Pages 256-271 CHAPTER XVI QUANTITY OF WATER REQUIRED FOR DOMESTIC AND OTHER PURPOSES Variation in rural and urban districts Purposes for which water is required Various estimates of amount required for different purposes Constant versus intermittent supplies Tables showing amount supplied in various towns Newcastle and Wolverhampton records Daily supply by London Water Companies Waste of water Unnecessary consumption Prevention of waste Saving effected by Deacon's meters at Liverpool, Exeter, and elsewhere Amount of water required in tropical climates Daily quantity required by various animals .... Pages 272-283 CHAPTER XVII SELECTION OF SOURCES OF WATER SUPPLY AND AMOUNT AVAILABLE FROM DIFFERENT SOURCES Various sources Finding water Water "finders" Selection of site for wells Drainage area The Stockport water supply Amount yielded by various water-bearing formations . Pages 284-304 CHAPTER XVIII WELLS AND THEIR CONSTRUCTION Shallow wells How usually constructed Improved methods of constructing Tube wells Koch's advice with reference to shallow we ll s Abyssinian tube wells Amount of water yielded by various tube wells Cost of sinking wells Cost of driving tubes Deep wells Pumping directly from tubes Pumping from storage reservoir Multiplication of tube wells to increase supply Defects in tube wells Yield of water from deep wells Deep wells in Queensland, South Australia, Victoria, Cape of Good Hope, United States, and other countries . . . Pages 305-331 xiv WATER SUPPLIES CHAPTER XIX PUMPS AND PUMPING MACHINERY Various types of pump Lifting pumps Plunger or force pumps Centrifugal pumps Bucket and plunger pump Quantity of water delivered by each stroke of pump "Efficiency " of pumps Height to which water can be raised (a) by manual labour, (b) by donkey working a gin, (c) by horse working a gin, by one horse- power engine Wind engines Water as a motive power Rams, turbines, and water- wheels : Fuel engines Hot-air engines Oil engines Gas engines Steam engines Horse-power required Pages 332-356 CHAPTER XX THE STORAGE OF WATER Impounding reservoirs Settling reservoirs Service reservoirs Classi- fication of waterworks Effect of storage Covered versus open reservoirs Capacity of storage reservoirs to compensate for the inequality of hourly consumption and provide reserve in case of fire Rain-water tanks Bouse cisterns . . Pages 357-368 CHAPTER XXI THE DISTRIBUTION OF WATER The "constant" system The "intermittent" system Conduits and aqueducts, size of, fall required Various kinds of mains Eytel- wein's formula Depth of mains Dead ends, advantages and disadvantages House service pipes, lead, tin-lined lead, wrought iron, galvanised iron Regulations made under the Metropolis Water Act, 1871 Pages 369-380 CHAPTER XXII THE LAW RELATING TO WATER SUPPLIES Land and water rights, voluntary and compulsory purchase of Sale of rights by limited owners Roadside waste land, ownership of Precautions to be taken when purchasing lands, springs, etc. Rights of riparian proprietors Water flowing in definite channels Underground water Waterwork Clauses Acts Water rates and rents Cost and maintenance of waterworks, by whom borne Parish Councils and water supplies The Public Health Act 1875 The Public Health (Water) Act 1875 The Limited CONTENTS xv Owners Reservoirs and Water Supply Further Facilities Act, 1877 Important legal decisions affecting water supplies Pages 381-399 CHAPTER XXIII RURAL AND VILLAGE WATER SUPPLIES General neglect to provide rural supplies, causes of Advantages of public supplies Description of typical works, with cost of works, cost of maintenance, water rates levied, etc. Spring water raised by hydraulic ram Gravitation works Spring water raised by steam pump Subsoil water raised by steam pump Subsoil water gravitation works Spring water raised by water-wheel Deep- well water raised by windmill Spring water pumped by turbine Deep-well water raised by an oil engine Spring water raised by a gas engine Table of rates Charges for domestic supply of water in various towns .... Pages 400-417 APPENDIX 1. Crenothrix, cause of disagreeable odours in water 2. Zinc- contaminated water, effect upon health 3. Plumbo-solvent action of moorland water 4. Pollution of water in reservoir, outbreak of typhoid fever 5. Pollution of water supply by melting snow, outbreak of typhoid fever 6. Pollution of water in mains 7. Pollution of a deep well near Edinburgh 8. Typhoid fever in the Bolan Pass 9. Self-purification of streams Pages 418-422 o* UNIVERSITY WATEE SUPPLIES CHAPTEE I WATER, ITS COMPOSITION, PROPERTIES, ETC. FEOM the time of Aristotle until the close of the eighteenth century, water was regarded as an elementary substance, that is, one which could not be split up or decomposed into any simpler forms of matter. In 1781 an English chemist, Henry Cavendish, discovered that when two gases, oxygen and hydrogen, were mixed together in certain proportions (two of hydrogen to one of oxygen) and an electric spark passed through the mixture, combination took place and water was formed. Many other ways have since been devised for causing these gases to combine and for demonstrating that water is the product formed. By other methods also water can be decomposed and made to yield the two elements which alone enter into its composition when pure. For example, if a strong current of electricity be passed through water, bubbles of gas are given off from each terminal or pole. At the one pole the gas consists of pure oxygen, at the other of pure hydrogen, and the volumes obtained are two of the latter to one of the former. As oxygen is sixteen times as heavy as hydrogen, the composition of pure water is as under : By volume. By weight. Oxygen ... 1 part . . 8 parts. Hydrogen ... 2 parts . . 1 part. B 2 WATER SUPPLIES Pure water is a chemical curiosity. The moisture which bedews the tube in which the mixture of hydrogen and oxygen has been exploded is water in its purest form. If, however, it be exposed to the air or be allowed to stand in contact with any substance (save perhaps some of the less oxidisable metals, as platinum and gold) it will absorb gases from the air or dissolve some of the material of the vessel in which it is placed, and from a chemical point of view is no longer pure. Pure water does not occur in nature, even rain water caught in mountainous districts far from the smoke of towns or the haunts of men contains traces of impurities taken up from the air. When the foreign sub- stances are present in so small quantities as not appreciably to affect the physical properties of the water, or to render it unfit for domestic and manufacturing purposes, it is popularly spoken of as " pure," and it is in this sense that the term " pure water " will in future be used throughout this book. Pure water, when viewed in small quantities, appears to be perfectly colourless, but when viewed in bulk, as in the white tiled baths at Buxton, and in certain Swiss lakes, it is seen to possess a beautiful greenish-blue tint. A very small amount of suspended or dissolved impurity is sufficient to obscure this colour. Impure waters almost invariably exhibit a colour varying from green to yellow and brown when examined in suitable tubes about two feet in length, but, as will be seen later, it does not always follow that a water with a brownish tint is too impure for domestic use. Pure water is absolutely devoid of odour and is destitute of taste. The purest is insipid, but if such a water be aerated by agitation with air or by nitration through a porous, air -containing medium, the insipidity disappears. Practically, water is incompressible, but the volume of a given weight varies very considerably with the temperature. With very few exceptions all fluids expand when heated and contract when cooled. The most important exception is water between certain temperatures. As the effect of heat upon water has a direct WATER, ITS COMPOSITION, PROPERTIES, ETC. 3 bearing upon certain points connected with water supplies, it is necessary briefly to consider the action of change of temperature. If a quantity of pounded ice, with a little water, be placed in a glass beaker in which two thermometers are placed, one at the bottom and the other near the surface of the mixture, it will be found that both indicate the same temperature, C. If now some source of heat be applied to the beaker, it will be observed that neither thermometer will indicate any increase of temperature until the last particle of ice is melted. The heat, as such, has disappeared, its effect upon the ice being not to raise its temperature but to liquefy it. The same fact can be proved by another simple experi- ment, which enables us also to measure the amount of heat which disappears or becomes latent. If one pint of water, at the temperature of C., be mixed with one pint of water at 79 C., the temperature of the mixture will be the mean, 39 '5 C. If, however, ice at C. be substituted for the cold water, the whole of the ice will melt, but the temperature of the resulting fluid will not be 39'5 C. but 0. Water at 0, i.e. at its freezing point, may be said to be ice plus heat. This heat, which becomes latent during the process of lique- faction, is again given off when water freezes. As the surface of a sheet of water freezes, the water, in the act of solidification, gives up a certain amount of heat. This raises the tempera- ture of the remaining water, and so the process of freezing or solidification is retarded. Were not this the case, during winter water would freeze with great rapidity, and the ice so formed would as rapidly melt when the weather became warmer. Such a condition of things would render all but the tropical and sub-tropical regions practically uninhabitable during certain portions of the year. As soon as the tempera- ture sank below zero, ice would so quickly form that our lakes, reservoirs, streams, etc., would contain only solid ice. Snows would melt so rapidly with a slight increase of temperature that most disastrous floods would follow. This sudden freezing also would result in the bursting of every water 4 WATER SUPPLIES main and pipe, since water in the act of solidification expands considerably, eleven pints of water when frozen forming twelve pints of ice, or, in other words, water expands one- eleventh of its volume in the act of freezing. The effects of this expansion are disastrous enough to water mains and pipes when the freezing process is retarded by the heat given off by the water as it solidifies ; but if the solidification took place suddenly, as soon as the temperature fell slightly below zero, the expansion, being uniform in every direction, would burst every pipe or vessel in which the water was contained. The force so exerted in the act of freezing is enormous. Thick iron shells filled with water and securely plugged are easily burst by exposure to the cold of a Canadian winter's night. Water is at its maximum density at 4 C. If cooled below that temperature it expands ; if the temperature is raised it also expands. It thus differs from nearly all other liquids, which at all temperatures between their freezing and boiling points expand when heated and contract when cooled. If a jar of water be exposed in an atmosphere below zero, and two thermometers are placed in the water, one at the bottom and the other near the surface, it will be found that the thermo- meter at the bottom records a continuously lower temperature than the one near the surface until 4 C. is reached. Up to this point the colder water, being heavier, has continued to fall to the bottom of the jar. Below this temperature the upper instrument will record the lower temperature, proving that at temperatures below 4 water becomes specifically lighter. If such were not the case the water at the bottom of the vessel would continue the colder and would be the first to freeze. Solidification would take place from below upwards. The result would be that during a severe winter our streams and lakes would become one mass of ice, which all the heat of the ensuing summer would be unable to melt. To quote Professor Roscoe, " If it were not for this apparently unimportant property our climate would be perfectly arctic, WATER, ITS COMPOSITION, PROPERTIES, ETC. 5 and Europe would in all probability be as uninhabitable as Melville Island." As it is, in large lakes and rivers the temperature of the deep water never falls below 4 during the winter, and the surface water when cooled to zero begins to freeze, and at the same time to liberate its latent heat, which raises the temperature of the layer beneath, and so retards the cooling process. That the habitability of such a large portion of the globe should depend upon these exceptional properties is a remarkable fact. At the sea-level water boils at 100 C. When the atmo- spheric pressure is decreased, as in ascending a mountain, or when the water-containing vessel is placed under the receiver of an air pump and a portion of the air exhausted, the boiling ^ point is lowered. On the summits of the highest mountains i T 1 0 CO l^ o o S s tauoduiaj 1-1 1-1 JZ5 o I p ,s ^ | CS ^ ^ 1 1^1 +3 ^2 ce EH 'c PH a < -^ * ^ S o ^ 1 ' '-M o ^ PH PH "3 r^ ^ fa g S 3 pq CO K 5 02 PH H ^ S .i 'S -: ^ K-^ d o ^ ^ Is 5 ?! S' 02 c c 6 d 6 o n i o 5 -Jj 1 1 1 O ^ 1- If pj cp ^ (X) "t^ S rH p| 1 2 PH li S O S c6 ^ T3" != J3" | pj i tn . 'oo . | -P ^ > rt ^n G f2PnC ^ ^ -S O 9 s O ?* <-> fei #'S>2 < [TJ 5 "" PH S I-H r^H hH rC hH PQ x ^ % HH *d P^.Sfa H fa' H fa c 5 p. 02 H ;H S-^ P3 ^ H fa P P H, PP 6 ^ l OO OS O fc I 1 t^ CO CO CO Oi CO t i 1 rH i : cp o p CO op O : OJ op Jo ;| o p o CO HH CO 00 poop p CO p CM 9 rH SO p 5 p o O O ^H O poop to p o p o i 1 O rH O O 9 rH ! 1 p o .2 1: ll 1 rl 01 UT2 O O O iO . CO CO CO CM CO CO ^ OS ** ^ CO O CO CO ' rH p oo 05 CO g S CO rH cp 1? T 1 O p CM Th ^ 00 ^ O O O rH o rH Ttl o o o g S Oi o O o o CO O . tfi CO CO CO T* OO 9 OO 1--. OS t^ 10^0^0*0 CO CO OO 00 00 CO CO CM CM CM 71 * do. do. do. Peaty and often acid 1 r2 Greenish yellow Yellowish ^o o ^3 I -M a | 4 6 o 'Ig o o o Vyrnwy Lake, Silurian ti V CO ii stone Coal Measures ^ 1 S stone Cultivated Cal- careous Cultivated Cal- careous a'nd OJ mal Chlorine within limit of error Chlorine in ex- X O) s 1 oj^ g * CD d S>0 Hi! co Q Liverpool _O 4^ ll 1 i 1 OT CO CM 1 5 CC \0 .2 ^ PH o W ^ 0) 5 S &C^ H S^ > o 1^ w CO "o 1 CO a* C 0> Is 4 X 60 6600 dTJ'c: H s p PQ d 5 CO c TJ > fi S odW ( _>- -s g O Massachusetts State. Board g 3 O OO 1 s rH (M CO ^ i 1 rH rH rH 3 S.H OO I 1 O5 i i WATER SUPPLIES H I I QaVJldAy rH CO OO t^ O OS O O -j}< CO V 11 11 1 VHMCXI CO O (N rH CO ?^P? - ios ^^ u ^saqSijj U3 CO rH T-l -*H 1-4 ^f OO p op CN OO 1O OO O CO CO OS os^t ThH< * o^eaaAV rHrHCO CO OO OO OS 00 (M CO rt< rH rHOOJ^ CO O * r co *"^ AVOT CO CO (N CO CO OS CM . CO 00 US * CO TH ,H rH CO CO rH O OS (M (N OS t^t^ i aSuiaAy CO CO O^ CO CO rH rH rH CO (M iJ rH rH CO O CO Q 05 ^ rH O rH H^ T^ (M t^CO I-l S8 IH 00 00 O O ^ CO oo : os rH S^: 1 *^S8AVO r J rHOCO > r2 g OJ Q 'S rt "S O H 03 pq K r^ Q> 2 ^ M CS Q 05 & ,3 S'Sl | J | O "^ ^ " c6 " ^ -fS fc -5 -2 ^ 3 ifl-gj 2 ^ 1 l?l C.) o **"* C11 "^ fl4 2 ' " o III llfl ll^ ll 'i .sT p,^ 1 p^-^ S i " a o p^S rt ^"^ r-( ^* O) ^ g^ 1 a, IH r!3 CO gr-H It^ 5 00 -*^ 03 g SS Hi^ -.3 OSt^ ill I-l (N CO Tf IO CO t^ CO OS O rH CHAPTEE IV SUBSOIL WATER THE subsoil or stratum immediately underlying the surface soil may be of a pervious or impervious character. If pervious a considerable portion of the rain falling upon the soil will pass down into it, if impervious only a relatively small portion will percolate, the larger portion running off as sur- FIG. 5. A, Pervious subsoil ; 4', Portion saturated with water ; B, Impervious stratum ; c, Spring. face water. Where such an impervious rock occurs covered only with the spongy debris of vegetation, saturated with water, we have bogs, marshes, and swamps. The district will probably be malarial and the water of a dangerous character. Where a pervious subsoil of sand, gravel, chalk, limestone, sandstone, or other rock overlies an impervious rock such as clay, granite, hard limestone, etc., a portion of nearly every rainfall enters the subsoil, and being held up by the impervious layer below tends to accumulate. The water thus held in the interstices of the rocks lying imme- diately beneath the soil is "subsoil" or "ground" water. Where the pervious subsoil fills in a hollow in the more im- 42 WATER SUPPLIES pervious stratum, as in so-called pockets of gravel, the ground may become waterlogged that is, completely saturated with water. If, however, at any one or more points the edge of the containing basin is depressed, water will overflow, form- ing a spring. Such overflow will only take place when the water in the porous rock has its surface level raised above that of the outlet. The portion below this will still remain stagnant. Where the porous subsoil rests upon a flat or sloping imper- vious substratum, the subsoil water will be constantly in motion, travelling towards the lowest point, where the imper- vious rock outcrops. There it will either issue as a spring, FIG. 6. .(, Pervious rock ; n, Subsoil water ; c, Spring ; />, Stream ; E, Clay or other impervious stratum. or act as the invisible feeder of a stream or lake. " The action of the soil in regard to water is in reality of a three- fold nature : it may transmit water as wine is transmitted by a strainer ; it may imbibe the moisture just as ink is soaked up by blotting-paper ; and it may hold or be saturated by water, as a sponge immersed in water is saturated by liquid which flows from it when the sponge is lifted out. Thus we have to distinguish between the permeability, the imbibition, and the saturation of a rock. The amount of surface water which percolates through the soil depends upon the permea- bility ; the amount retained as moisture of the soil depends upon the imbibition ; the amount which can be held by the subsoil as ground water depends upon the saturation." l Clay exhibits in a high degree the property of imbibing water, but 1 Miers and Crosskey, The Soil in relation to Health. SUBSOIL WATER 43 it is only very slightly permeable. Coarse gravels, on the other hand, are exceedingly permeable, but imbibe little, and have little storage capacity. The coarser the grain of any rock, the more freely will water traverse it, and the springs which it feeds will be more quickly affected by the rainfall. The water which penetrates the subsoil will either eventually flow out as springs (which will become dry unless the rain falls with sufficient frequency to keep up the supply of ground water), or if, from the contour of the impervious stratum below, the springs and outcrop are not at the lowest level of the water-bearing stratum, a certain amount of water will always be retained, forming, as it were, an underground reservoir. If, by pumping or otherwise, water be drawn from this reservoir, the outflow from the outcrop will be decreased by the amount so removed, and if sufficient be pumped the springs will cease to flow. The level of the water in the subsoil varies in different places and in the same place at different times. Where the porous stratum is of great thickness the water-level may be at a considerable depth, depending chiefly upon the elevation of the outcrop. The level also will vary with the rainfall, rising when the amount percolating is in excess of that flowing from the springs, or being artificially removed from wells, and falling when the percolation is less that the outflow. The rapidity with which the rise and fall follow the variations in the rainfall depends on the permeability of the subsoil and its depth. Prestwich states that on the chalk hills it takes from four to six months for the rainfall to reach the water-level if at a depth of 200 to 300 feet. On gravel and sand, with a water-level only a few feet from the surface, the rain would be absorbed and percolate much more rapidly, but probably would not affect the ground water level for many days. The varying level of the river into which the ground water is discharged will also affect its height, since when the river is in flood the ground water will be held back and rise. The fluctuation will be most marked in wells near the river, and least in those at a 44 WATER SUPPLIES distance. When the ground water enters the sea even the rise and fall of the tide may cause the height of the water to vary. The amount of water which can be retained in a rock varies considerably. 'Chalk and sand can hold about one- third their bulk of water ; oolite one-fifth ; magnesian lime- stone one-fourth ; compact sandstone and pebble beds one- eighth ; granite one-fortieth. Expressed in other words, one cubic yard of chalk or sand saturated with water would contain from 50 to 60 gallons of water, and an area of one acre 3 feet thick would contain about 260,000 gallons. Except in depressions in the impervious substratum which have no outlet, the water in the subsoil is in constant motion, travelling towards the outflow. The rate of this movement is affected by the porosity of the ground, its slope, freedom of outlet, and many other factors. At Munich, Professor Pettenkofer finds that the subsoil water moves towards the Isar at a rate of about 15 feet per day, whilst at Berlin the movement towards the Spree is barely perceptible. At Buda- Pesth the mean rate, according to Fodor, is 174 feet daily. The height of the subsoil water can be ascertained from the level of the water in the wells, and its variations will be indi- cated by the rise and fall of the water-level. This under- ground sheet of water may be of considerable extent, but its surface is not necessarily or even usually horizontal. It will slope towards the outlet, not uniformly, but with a curved surface. When water is abstracted at any point, as from a well, a portion of the water in the subsoil around drains into the well to replace that removed. The water-level for a certain distance is lowered, the curved surface sloping less and less as it recedes from the well (Fig. 13). The extent of area drained will vary with the degree to which the level of the water in the well is depressed, and with the permeability of the subsoil. Usually the radius of this drainage area is taken as twice the depth of the well, but it may under certain circumstances be much more than this. The whole of the rain falling upon a pervious soil does not SUBSOIL WATER 45 percolate into it. Some will run off the surface, the amount varying with the slope and the nature of the surface ; some will be lost by evaporation, not only from the surface of the ground, but also from the leaves of herbs and trees. Dr. Dalton, at Manchester, found that only 25 per cent of the rainfall percolated to a depth of 3 feet. Mr. Dickenson, at King's Langley, on a grass -covered gravelly loam, found that 42 '4 per cent reached that depth. Dr. Gilbert and Mr. Lawes, at Rothamstead, found that about 37 per cent was collected at a depth of 20 inches, 36 per cent at 40 inches, and 29 per cent at 60 inches. Since the loss by evaporation in the summer is very great, little or no water may reach the underground reservoir during the warmer months (April to September). At Nash Mills, Hemel Hempstead, as an average of twenty-nine years' observations, the percolation in summer was found to be about 14 per cent, in winter 61 per cent, during the whole year 37 per cent. The soil here was chalky. On loose sands and gravel a much larger proportion would undoubtedly percolate, whilst in sandstones probably only about 25 per cent, and in limestones even a smaller quantity, would reach the ground water. The most favour- able watershed is one which is fairly level, sandy or gravelly, and having few or no outlets ; so that nearly all the water which percolates goes to increase the underground supply. Where the outlets are free, naturally the store of water will never be so large, since it is being constantly drained away. Water is obtained from the subsoil by driving tubes or by sinking wells, and these may have galleries driven in various directions to increase the supply. The permanent yield of such a well will depend upon the area of the water- shed by which the water is collected and the porosity of the subsoil. During dry weather the pumping operations will lower the level of the water and provide space for the water which will percolate during the wet season. To obtain a permanent supply of a fixed quantity of water, the proportion of the rain falling upon the contributing area which can be 46 WATER SUPPLIES collected must be equal to the quantity which it is desired to abstract. If the area of the watershed draining towards the proposed well be known, and the rainfall, the depth of ground water required to furnish a given daily supply may be approximately calculated. Let us assume that the rain- fall records prove that 120 days' storage is required, and that the amount of water to be raised daily is 250,000 gallons, and that the subsoil is sand or gravel. Such a subsoil, when saturated, will contain about 35 per cent of water ; but the whole of this cannot be removed, only about 25 per cent will run out when the water-level is lowered. In order to obtain this 250,000 gallons daily it will be found by calculation that it is necessary to have storage equivalent to 40 acres of ground, in which the water-level can be lowered 9 feet. If a superficial examination renders it probable that this amount of storage is available, a series of tests must be carried out to confirm it. For this purpose a number of test wells are driven during the dry season, and the change produced by long-continued pumping observed. The depth to which the water surface is lowered at the wells and at various distances from the wells will furnish the engineer with the required information. The water from so-called shallow wells is subsoil water, and in most villages and nearly all rural districts such wells are the chief source from which water is derived. As a well only drains the ground for a limited distance around, where a larger supply is required other wells must be sunk or galleries be driven in various directions below the ground water level. On gently sloping ground a chain of wells may be sunk and connected together. In a valley through which flows a stream liable to pollution, pure water may sometimes be obtained by sinking wells along the foot of the hills, and so intercepting the ground water on its way to the stream. If the bed of the stream is formed of permeable rock, it will be saturated with water flowing slowly in the same direction as the stream. Such a subterranean river may even SUBSOIL WATER 47 convey more water than the visible stream. In the Thames valley it is estimated that the flow beneath the river con- siderably exceeds that of the river itself. In seasons of drought the subterranean flow may continue long after the bed of the stream has become dry, and at such times water may often be obtained by sinking a well. In galleries sunk along the course of streams or near the borders of lakes, where the subsoil is pervious, when the level of the water in the galleries is lowered below that of the surface of the stream by pumping or in any other way, water may flow from the river or lake into the galleries. Percolation out- wards through the silt or mud at the bottom of rivers and pools can only take place slowly, and no definite measure- ments have ever been obtained of the amount. Where the quantity of water removed from the galleries does not reduce the level below that of the free water surface, the whole supply is derived from the ground water intercepted on its way to the stream, and only when the level is reduced below the free water surface is the supply supplemented by back- ward percolation. The quality of subsoil water will vary with the character of the subsoil and the proximity to human habitations. In the chalk, lias, oolite, sandstone, and limestone districts the water will be hard, but the most ancient rocks, the Yoredale and millstone grits, and sands and gravel generally, yield soft water, if uncontaminated. The living earth has such remarkable powers of purification and filtration, and the subsoil beneath is so effective a filter, that natural ground water is almost free from germs (often it is absolutely free) and from organic matter. This natural process of purifica- tion will be described more fully in a later section. As usually derived from shallow wells, the subsoil water is almost invariably subject to contamination. The Commis- sioners appointed to examine the Domestic Water Supply of Great Britain reported that the most dangerous water is "shallow well water, when the wells are situated, as is 48 WATER SUPPLIES usually the case, near privies, drains, or cesspools. Such water often consists largely of the leakage and soakage from receptacles for human excrements ; but, notwithstanding the presence of these disgusting and dangerous matters, it is generally bright, sparkling, and palatable." In Table IV. the highest and lowest results are given of the analysis of large numbers of waters from various geological sources. The majority of the samples, however, were very impure, and the lowest results only can be considered typical of pure water from these sources. Table III. contains recent analyses of a number of town water supplies derived from the subsoil. It will be observed that in many cases nitrates (as indicated by the nitric nitrogen) are present in considerable amount, and as these salts are derived from the oxidation of organic matter, such as sewage, manure, decaying vegetables, etc., waters containing such quantities of nitrates are often looked upon with considerable suspicion, and some chemists, relying upon their analytical results alone, absolutely con- demn these waters as dangerous to health. Koch, 1 com- paring the processes of artificial and natural filtration, says : "As a rule, the soil is of a material much more finely granulated than the comparatively coarse-grained sand of the filter, and it is fair to expect that the subsoil water, after passing the sufficiently thick layers of this finely granulated soil, will be either very poor in micro-organisms, or quite free from them. This is confirmed by the investigations of C. Fraenkel, who has shown that subsoil water, even in a soil which has been much and for a long period contaminated, as is the case in Berlin, is quite free from germs. In other places the same results have followed from investigations made on this point. We have, therefore, no reason to keep out of consumption the subsoil water, which can be found nearly everywhere. On the contrary, we cannot find a better - filtered water and one more protected against infection. The only difficulty is to bring this perfectly 1 Water Filtration and Cholera. Translated by A. J. A. Ball. SUBSOIL WATER 49 purified water into consumption without its being later on again contaminated and infected. In this respect great errors are still most inexplicably made everywhere." Wells as ordinarily constructed yield polluted water because no attempt is made to keep out surface water. Not only can the pure water enter at the bottom of the well, but the less perfectly purified can enter at the sides, and the impure surface water can gain access at the top. Often the wells are left open, and so unprotected that filth can be washed in with every rainfall, or, if covered, the dome is not water-tight, nor the ground above solid, nor of such a character or of such a depth as to purify the water passing through it. Drains of most primitive construction are often placed near to carry away the waste water from the purnp, but used also for slop water of all kinds. Waters from such wells are notoriously liable to become infected, and have often caused outbreaks of typhoid fever and cholera. The proper construction of wells and the alteration of existing wells, so as to render them safe, are subjects of such vital importance that they will be discussed in a special chapter. Koch is so convinced of the absolute nature of the security from the danger of infection afforded by the use of subsoil water properly collected and stored, that he has proposed that the Berlin waterworks should be so altered as to supply the city with subsoil water only. Budapest derives its water supply from the subsoil along the banks of the Danube, in which a chain of wells is sunk, and the outbreak of cholera in 1893 was attributed to the use of this water. In the State of Massachusetts, forty-two towns varying in population from 2000 to 25,000 have public water supplies taken from the ground. The largest supplies are taken from localities in the vicinity of large bodies or streams of water. At Newton nearly 2,000,000 gallons of water are pumped daily from galleries extending for about three-quarters of a mile along the course of the river. At Waltham a well 40 feet in diameter is believed to be cap- E 50 WATER SUPPLIES able of yielding 1,500,000 gallons daily in a dry season. Maiden and Revere may be cited as examples of towns sup- plied exclusively with subsoil water, not supplemented by water percolating from lakes or streams. 1 "At Maiden the amount pumped in 1890, 746,446 gallons daily, represented a collection of 9 '7 inches (or 20 per cent of the total rainfall of 49 inches) upon a direct watershed estimated at T61 square miles. At Revere the pumping for the year, 465,491 gallons daily, represented a collection of 12*5 inches (25 per cent of the total rainfall of 50 inches) upon a watershed of 0'78 square mile." But "it is probable that the amount which has been pumped is more than could be pumped after one or two years of low rainfall. At Revere particularly, experience has shown that the storage capacity of the ground is very large, so that when the water-table is reduced to a very low level during the summer, the ground will not fill before the next summer, unless the amount of rainfall is above the average." Where it is desired to obtain water from the porous subsoil, the direction of the flow of the ground water must be ascer- tained. This will be towards the springs, lakes, streams, or rivers forming the outflow. The ground water will have its highest level at the point most distant from the outflow, but most water will be obtainable near the outflow, unless the porous subsoil rests in a depression in the impervious rocks beneath, when most water can be procured where the depres- sion is greatest. In an inhabited district the purest water will be found on that side which is farthest from the outflow, since all the impurities entering the subsoil will be carried in the direction of flow of the underground water. For this reason a pure water may sometimes be found at one side of a house, when that from the opposite side is polluted. Where a patch of gravel is bounded by streams on two sides, the ground water will be travelling in both directions, and that at one side may be much less impure than that from the 1 Report of State Board of Health, 1890. SUBSOIL WATER 51 other. Thus in Fig. 6, if the village stand upon one side of the hill, it will affect only the ground water at that side, the water on the opposite side escaping contamination. The extraordinary extent to which the subsoil water can be affected by pollution from inhabited houses, highly cultivated land, etc., is indicated by the analyses given in Table IV. When examining recently the water from a gravel patch about one square mile in extent, and with a population of about 1400 persons upon it, I found that the water along three sides of the patch was remarkably constant and uniform in composition, and very free from organic impurity, whilst that from the neighbourhood of the village, and between the village and the river, the principal outflow, varied considerably, and was more or less impure. In Table III. the analyses, Writtle, Nos. 1, 2, and 3, are of waters taken from the gravel at the three first-mentioned sides ; Nos. 4, 5, and 6 are of water from wells in the village. The difference is entirely due to the soakage of slop-water, sewage from defec- tive drains, sewers, cesspit, and cesspools, into the subsoil. In some cases the filth had been very fully oxidised before reaching the well, in others this oxidation was not nearly so complete. Such waters are, of course, quite unfit for domestic use. Where the surface soil has been removed, as in the neighbourhood of inhabited houses, the purifying influence of the living earth is, of course, lost, and where the porous stratum of subsoil is thin, the purification by oxidation and filtration is but limited. Where both these conditions occur, the subsoil water must of necessity be very impure. Koch's eulogy of the subsoil as a source of water supply must there- fore be limited to those districts in which the population is scattered, and the subsoil of sufficient depth to secure efficient filtration and purification. Where both these conditions obtain, the ground may yield a water of the highest quality, but where these conditions are not fulfilled, there will always be impurity and risk. WATER SUPPLIES PC s 3 $ 2 p 13 co s sanoii t ui "BIUOHlHiy uiuommv ' 88JJ QQ 9 9 9 9 5 9 9 97^ CO rH CO 9 9 p p p p p M S SrS e ^ sll B- |e.sl |S11 ^ rrpn > SUBSOIL WATER 53 1 >s TJ ' 1 rd rd ^ . g 3 JO '~ - 0} i i*. 3w IS = ; H : - - - ; & Q S a iO O o o .... (M l^ CO OO 5C o : CO 00 r-H l^ IO 50 -I rH OJ _ p P p p rt p p p ppppp -f3 rH CO -* CO CN 5O CN rt< r( i 1 i 1 T t CN 10 rH 10 -N O o o o o O O O O r-H O p p p 1 o p O rH O O O rH O O rH O p p p p o s o op kO . O O 00000 p 00 5O r-H O CN CN 10 I-H O OO r-H 5O O CM r-i CN CO rH CN o ifl> p .... 10 O 5O 00 l^ CO 5O 5O 01 lO CN 01 '- | T 1 II rH I-H i-H tN O 5O O O O O O O ** o , 1 oo o CN CO OO rH rH : CM : : CO rH OO CN J^- Oi O CN CO CO O CO rH i 1 CO % . a o ^ 1 13 c. *o * h " ~ ., ^ o o g a> -2 ^o " * " ' "rp-flj "o O H ^ Q 3 |- 1 2 I e 3 -3 3 S^ ^2? 1' : : : : * O p ^^ - m O t-. o " $ GO a "- | - s" a> | a> ,1 2 Q> ^ S rH 1-1 C^ CO ^ O 50 7^ ^ 3 o c6 p^ ^ G "^^ ^ ^ r^H ^ -j rH pg ,0 ^^ O c rH ^j ^ >. C6 ^ *""* t>- 4-5 d W rg 1 f 1 ^^^ > ^ ^ o 02 PQ 5 54 WATER SUPPLIES . GO . M 02 +3 O Q) B o <* 8 GQ . o ^ "E o > I a a o o p H O 1 2 r>- M x-^ M rH ' O g M S O S^ a ^ - | 3 ^ m a 2 "Si I II w ^ un p -TH cO rHrH (N (MiMCO lO(M(MCq 10 o -O-^tlC p p p . p 01 O p-l p-l i I TO VO rH 0-jH 99 iOt^ 9 *P C. Tt< CO kO ko4t- O rH rH <^(N COJ<: i I CO i^ rH (N O 1O O CO l^ CO CO O 00 t^ ^*-j y^ ^-j t-i r* ^ts -tent "S ^ 55 -S'S rt go | 5 I n3 ST! p-i a -S -|^i!^i;*1 mill ^13 ml 'K H l s|s TjH ^ 1^.1 CO rH CO rH CHAPTER VI DEEP-WELL WATERS THE term " deep " in reference to wells is somewhat ambigu- ous, since different writers attribute to it different meanings. By some, any well over 50 feet in depth is called "deep," whatever the character of the stratum in which it is sunk, or the strata through which it passes. By others the term is used without any reference to actual depth, but to imply that the well is sunk through some impervious stratum into a water-bearing formation lying beneath. Such writers regard all wells as " shallow," whatever their depth, if they are sunk into and yield water from a superficial stratum. Water in the interstices of a rock overlaid by an impervious formation must have travelled some distance (often many miles) from the outcrop upon which the rain furnishing it fell ; hence nitration and oxidation is as a rule very perfect. But where a pervious formation is so thick that the water- level is 50 feet below the ground surface, it is evident that in percolating to this depth the water will have become so purified as to approach the subterranean water above referred to in character. Such being the case, it is best to consider such deep superficial wells as "deep." Deep wells passing through impervious into pervious and water-bearing strata are best designated as Artesian, although this name is often reserved for those deep wells from which water actually overflows. The first wells of this character were probably sunk in China ; they were common in the East at a very early DEEP- WELL WATERS 71 period. Centuries ago they were also sunk in the province of Artois in France. One such well there has undoubtedly yielded a continuous supply of water since the year 1126 A.D. At Grenelle in this province a large boring was com- menced in 1835, and was carried to a depth of about 1800 feet before the water-bearing sand was reached. The water then rushed in and rose some 60 feet above the surface of the ground, the flow being nearly 1,000,000 gallons per day. FIG. 8. With the imperfect appliances of that period, the well took six years to bore. Artesium being the ancient name for Artois, all such wells have since been called Artesian. The various kinds of deep well are illustrated by the above diagram, Fig. 8. The water-level in the formation c being at d, it is evident that a well sunk at A would not pass through the superficial impervious stratum b, yet would be deeper than the well sunk at B, passing through this formation to reach the same source of water. The level of the ground at C being considerably below the water-level d, water would overflow from the well at C. The latter, therefore, is a true Artesian well, or we may call it an overflowing Artesian well to distinguish it from B. Very little consideration will render it obvious that per- 72 WATER SUPPLIES vious strata which lie below the sea-level must retain within them all the water absorbed at their outcrop. Formations of this character, with extensive exposed surfaces, passing under other more superficial strata, may store enormous amounts of water, and if they do not reach too great a depth, which is rarely the case, water may be obtained from them by boring or sinking a well. The greater the depth to which the boring passes, the greater the supply of water obtainable. Thus in Fig. 8, as soon as the water-level in c became de- pressed by pumping from A, B, or C, below the bottom of A, that well would cease to yield. If the water-level became still more depressed B also might fail, whilst C would continue to furnish a supply. This only applies when the pumping at the lower level is withdrawing more water than is passing into the outcrop from the rainfall. When such is not the case, the effect of one well upon another, if some distance apart, will be inappreciable. If the whole of the pervious stratum c be not saturated with water, the conditions will be different, water will be travelling in the direction from A to C, either towards the sea, some river, or spring, (unless, as occasionally may occur, there be no outlet), and the movement of the water present in the rock may be looked upon as analogous to that of a subterranean river, or as that of water in a cistern supplied at the top and being drawn off at the bottom. According to the cistern theory, pumping will reduce the level of the water without stopping the 'leakage" from the bottom, whilst on the river theory pumping will chiefly affect the leakage, since abstraction of water from any point in a river must decrease the flow of water past that point. The two views were ably argued before the Royal Commission on Metropolitan Water Supply, and after hearing the evidence of Sir John Evans and Mr. Whitaker in favour of the " cistern " theory, and of Baldwin Latham in favour gf the " river " theory, the Commissioners reported as follows : " We are of opinion that the analogy of a cistern is in- DEEP- WELL WATERS 73 accurate and misleading when used in relation to streams at a considerable distance from the points where pumping is carried on. A waterworks well is itself a typical cistern ; the pumps are not unfrequently submerged many feet, and when pumping commences it is the bottom water that is withdrawn, and in consequence of losing its support the upper water is proportionally lowered. . . . But in addition to this vertical and horizontal lowering (of the water surface) in the open well, there goes on simultaneously a lowering of a different character in the chalk around the well. " Immediately adjoining and outside an unlined chalk well, the water lowers pari passti with that inside, but the same horizontal plane is not continued outwards. The water cannot pass through the crevices in the chalk to the well without a certain amount of fall or slope, this being necessary to overcome the friction of its passage. Hence the surface of the water in the emptying chalk rises from the well in all directions at a gradient more or less steep, in relation to the openness or closeness of the passages. These slopes will nowhere probably form a symmetrical or regular cone-shaped depression having the well as its centre, but slopes at varying angles modified by circumstances are undoubtedly required if the supply to a well is to be maintained whilst pumping is going on. "It is only necessary to follow out this idea to a distance of miles from the well to realise clearly that the cistern theory is untenable. In the open well the upper water is supported directly by that below it, and when the support is removed the surface is immediately and vertically depressed. Out in the body of the chalk the upper water is only partially sup- ported by that below it, and mainly by the chalk in and upon which it lies and flows ; and this being so, the analogy of a river is much more apt and accurate than that of a cistern. Mr. Baldwin Latham and other witnesses were therefore more nearly right than Sir John Evans, when they said that pump- ing from a well tapping an underground stream flowing in a 74 WATER SUTPLIES known direction mainly affected the water below the well, and had little effect on that above the well." The same reasoning applies not only to the chalk, but also to all porous underground strata containing water under similar conditions. But few deep wells are sunk into the Devonian rocks, millstone grit, coal measures, or magnesian limestone, the probability of obtaining water therefrom being in most cases very problematical. The new red sandstone, oolites, and chalk are the great subterranean water-bearing strata, the lias, greensands, Hastings, and Thanet sands having smaller outcrops, and being much thinner, and not so certainly con- tinuous, yield much more limited supplies. The new red sandstone is an exceedingly effectual filtering medium, and from the great extent of this formation vast quantities of the purest water are stored in it, and often can be rendered available at a comparatively slight expense. The oolites, according to the R. P. C., " contain vast volumes of magnifi- cent water stored in their pores and fissures . . . and it cannot be doubted that a considerable proportion of this could be secured for domestic supply in its pristine condition of purity at a moderate cost." The chalk formation is one of the most absorbent ; therefore a large proportion of the rain- fall upon its outcrop passes into it and becomes thoroughly filtered and purified. The R. P. C. found the deep-well waters from the chalk "almost invariably colourless, palatable, and brilliantly clear." " The chalk," they say, " constitutes magnificent underground reservoirs, in which vast volumes of water are not only rendered and kept pure, but stored and preserved at a uniform temperature of about 10 C. (50 F.), so as to be cool and refreshing in summer, and far removed from the freezing-point in winter. It would probably be im- possible to devise, even regardless of expense, any artificial arrangement for the storage of water that could secure more favourable conditions than those naturally and gratuitously afforded by the chalk, and there is reason to believe that the DEEP-WELL WATERS 75 more this stratum is drawn upon for its abundant and ex- cellent water the better will its qualities as a storage medium become. Every 1,000,000 gallons of water abstracted from the chalk carries with it in solution, on an average, 1 j tons of chalk, through which it has percolated, and this makes room for an additional volume of about 110 gallons of water. The porosity and sponginess of the chalk must therefore go on augmenting, and the yield from the wells judiciously sunk ought within certain limits to increase with their age." Strange as it may appear, this does not apply to waters from the chalk in certain districts which, instead of being hard, as is usually the case, are exceptionally soft, containing sometimes not more than two grains of chalk in solution in each gallon. Such exceptions prove that the underground sheet of water is not continuous. As previously explained, this is occasioned chiefly by faults interrupting the continuity of the strata, and such faults may seriously affect the supply obtainable from any particular well. Besides such faults, various foldings and irregularities often occur, dividing and subdividing the subterranean reservoir, cutting off more or less completely one compartment from another, and limiting the supply. Before sinking a deep well, therefore, many points have to be care- fully considered if the possibilities of failure are to be reduced to a minimum. The chief are : 1 . The extent and character of the absorbing area or out- crop, whether bare or covered with drift, whether level, undulating, or hilly ; its elevation above the district proposed to be supplied by the wells ; the density of the population upon it, or discharging their sewage thereon. Notwithstanding the purify- ing action of porous rock, it is not desirable to have a dense population upon the outcrop, as in the course of time the water may become affected. Many wells have had to be closed for this reason. At Liverpool, 76 WATER SUPPLIES for instance, several deep wells belonging to the Corporation became polluted by the population on the collecting area, and had to be abandoned. Where the subterranean water is chiefly collected in and travels through fissures this danger is accentu- ated. The extent of the absorbing area is often difficult to determine, as implicit reliance cannot be placed on maps. The sections at the surface, by which the geological structure was determined at the time of the survey, are occasionally misleading. 2. The average rainfall for a number of years. This being known, and the nature of the surface determined, a rough estimate of the amount of water absorbed may be formed (vide Chap. XVII.). But the outcrop may receive the drainage of a neighbouring impervious area, or, on the other hand, the contour or surface of the outcrop may be such as to throw off an unusual proportion of the rainfall, or much of that absorbed may flow away from springs. The levels of the springs must be studied to ascertain the direction of flow of the underground water, and their positions may lead to important inferences with reference to the continuity or otherwise of the water-bearing stratum, the presence of faults, crumplings, or other irregu- larities. 3. The continuity of the water-bearing strata and their super- ficial area and thickness. The maps issued by the Geological Survey show the position and throw of all known faults, but trial bores have frequently to be made to ascertain whether others exist, unless their absence is proved by existing wells. The study of data obtained from recorded well sections, or by the results of trial bores, will give an idea of the thick- ness and extent of the porous stratum. The thick- ness may vary considerably. Thus the chalk at Norwich is nearly 1200 feet thick, in Wiltshire 800 feet, in DEEP- WELL WATERS 77 Surrey 350 to 400 feet, in East Kent 800 feet, at Harwich 888 feet, at Kentish Town 640 feet. The lower greensand which lies beneath the chalk has a thickness of probably 600 feet in the Isle of Wight, but it rapidly thins away and appears to be absent under London. As an instance of the difficulties met with in determining the extent of an under- ground water-bearing deposit, and of the unrelia- bility of maps, Mr. Hodson, C.E., states 1 that when investigating "an area of lower greensand, which the Ordnance Survey showed as occupying an area of about 8| square miles, of which the outflow lay to the south-west, a careful examination proved that a main anticlinal existed which brought up an under- ground ridge of impervious Weald clay, which, although not apparent on the surface, effectively divided the underground sheet of water, and diverted to an outflow on the south-east the water absorbed on 3J miles of the watershed, leaving only 5| miles as possibly available. In addition to this the evi- dence afforded by the springs conclusively showed that other smaller anticlinals existed, which held up the water as in a series of troughs, which made it very doubtful whether more than one square mile could be commanded by any particular well ; whilst to complete the uncertainty, notwithstanding the most persistent efforts, it was impossible to discover all the lower greensand area given by the map, and a large district clearly marked as upper greensand was just as clearly gault." 4. The selection of a site for the well. Underground water not flowing in a well-defined channel, there are no laws conferring prescriptive rights of property ; hence if a well be so placed that its supply of water 1 A paper on Underground Water Supplies, communicated to the Incorporated Association of Municipal Engineers, May 1893. 78 WATER SUPPLIES is affected by the pumping from another well, there is no remedy at law. A site, therefore, should be chosen so as to tap the water at a point where it is least likely to be influenced by other wells (vide page 72). The multiplication of deep wells in and around London has lowered the water-level consider- ably, and in many parts of Essex, wells which were sunk fifty years ago, and then overflowed, only yield water when raised by pumps. In many instances, where the wells had ceased to yield, the deepening of the reservoir (or sunk portion of the well) or the lengthening of the pump pipe has restored the supply. The advantages of underground water supplies wherever obtainable, as compared with impounding schemes, are that large reservoirs are not required, very little land is wanted, no compensation water has to be provided, or water rights acquired from neighbouring landowners, filter beds are un- necessary, and the possibility of the water becoming polluted is much less. Against these advantages must be placed the cost of pumping; but "in these days of modern high-class pumping machinery," Mr. Hodson says, " the additional cost is so trifling as not to be worthy of serious consideration ; in fact, the expenses of pumping to a moderate height with good machinery are even less than the annual charges for interest and working expenses of filter beds alone." These remarks, of course, apply only to comparatively large centres of popula- tion. The expense of boring a well to any considerable depth prevents such supplies being obtained for single houses or small communities, except in certain districts where no other source is available. The mode of construction, cost, etc., will be discussed in the section on "Wells and Well Sinking." The distance within which one deep well can affect another in a continuous stratum depends upon many circumstances, DEEP-WELL WATERS 79 such as the porosity of the rock, presence of fissures and their direction, etc. In London there are wells within very few yards of each other, the supplies from which appear to be unaffected by their contiguity. On the other hand the Windsor Well, 210 feet deep, belonging to the Liverpool Corporation, is said to have affected the surrounding wells to a maximum distance of If miles. In the Lea valley the underground water-level has been carefully ascertained. From Chadwell springs to Cheshunt there is a fall of 4 feet per mile ; from Cheshunt to Waltham Abbey 18 feet per mile, and from Cheshunt to Hoe Lane 11 feet per mile. Between Hoe Lane and Walthamstow the fall averages 9 feet, whilst between here and the city the fall varies from 22 to 32 feet per mile. The increased fall south of Cheshunt is doubtless due to the pumping under London, which is abstracting more water in a given time than can pass through the chalk, compressed as it is by great thickness of clay above it. The effect, therefore, of the excessive ab- straction of water from the deep wells in London is affecting the water-level, or plain of saturation, to a distance of 10 or 12 miles north of the city. The following well sections, typical of those in and around London, are taken from Whitaker's Geology of London : BANK OF COLD BATH COVENTGARDEN ENGLAND. FIELDS. MARKET. Thick- ness. Depth. Thick- ness. Depth. Thick- ness. Depth. River Gravel and made ground 26 26 24 24 25 25 London Clay 111 137 45 69 135 160 Woolwich and Reading Beds . Thanet Sand . 5Si 39" 195 234i 55 8 124 132 J-100 260 Chalk 100 33H 20 152 98 358 8o WATER SUPPLIES SOUTHEND WATER- WORKS, ESSEX. WALTHAM CROSS, HERTS. STREATHAM COMMON, SURREY. Thick- ness. Depth. Thick- ness. Depth. Thick- ness. Depth. Surface Soil 3 3 (Gravel) 13| 134 (Mould) 2 2 London Clay 414 417 64^ 78 178 180 Sands . 181 598 64 142 195 285 Chalk . 302 900 ~~ 142 + 285 + The average depth of tube wells in London is about 400 feet, and in most instances the deep-well pump has to be fixed from 200 to 300 feet from the surface. Messrs. Isler and Company, who have bored many of these wells, state that the yield obtained varies from 1800 to 7200 gallons per hour from single bore holes. At Sleaford, in Lincolnshire, Messrs. Le Grand and Sutcliff recently bored a well for Messrs. Bass and Company's maltings. At a depth of 156 feet in the limestone beds of the lower oolite water was reached, and rushed out of the bore pipe 3 feet above the surface at the rate of over 12,000 gallons per hour, or nearly a ton of water per minute. By enlarging the boring and sinking to 177 feet the yield was increased to 30,000 gallons per hour. The towns of Long Eaton, Melbourne, and Castle Doning- ton have combined and obtained a supply of water from a deep well in the millstone grit at Stanton Barn. The scheme was devised by and carried out under the immediate super- vision of Mr. George Hodson, C.E. A well 70 feet deep was sunk, and from the bottom of this 750 yards of headings were driven, about 6 feet high by 5^ feet wide. Two bore holes, each 10 inches in diameter, were sunk to a depth -of about 300 feet, and lined with perforated steel tubes where they passed through water-bearing beds. The yield of water from these was found to be nearly 900,000 gallons per day. The population to be supplied is about 16,000, but it is estimated that in thirty years this will have increased to DEEP- WELL WATERS 81 25,000. The engineer is of opinion that the above yield FIG. 9. Illustrates the overflow from an Artesian well recently bored at Bourn, Lincolnshire, by Messrs. C. Isler and Company, for the supply of the town of Spalding. The overflow is at the rate of about 5,000,000 gallons per day, and is probably the most prolific underground spring yet tapped in England. The boring is only 134 feet deep. allows an ample margin for periods of drought and all other G 82 WATER SUPPLIES contingencies. From the well the water is pumped into a covered reservoir on a hill at such an elevation that the three towns mentioned can be supplied by gravitation therefrom. The pumps and pumping machinery are in duplicate, and are capable of raising 60,000 gallons of water per hour. The total cost of the completed works for the three districts was a little under 45,000. From time to time proposals have been made to further increase the supply of deep- well water for the City of London, and the whole subject has recently been fully investigated and reported upon by a Royal Commission. It is calculated that 40,000,000 gallons a day is obtainable from wells in the Lea valley, or 27,500,000 more than is at present being pumped ; from wells in the Kent Company's district 27,500,000 gallons, or 11,000,000 a day more that at present. The data and reasoning upon which such estimates are based may be illus- trated from that portion of the Commissioners' Report referring to the Lea valley. 1. The area of the collecting surface is estimated at 422 square miles, a portion consisting of bare chalk, or chalk covered with permeables, the remainder of chalk covered with partially or wholly impermeable beds draining on to the chalk. 2. The mean annual rainfall of a long term over this area is 26 '5 inches, the average of three consecutive dry years is 22 '8 inches, and the fall in the driest year 19 inches. 3. In the Thames valley the average annual evaporation is 16 inches, and in the driest year 14. Assuming the same to hold in the Lea watershed, the evaporation on an average of three consecutive dry years would be about 14*8 inches, leaving 8 inches to run off into the rivers or to percolate into the ground. Of that which gets into the ground a portion is returned to the river. From measurements made as to the yearly discharge at Field's Weir, above which the river receives the whole of the drainage of this area, the mean discharge represents 4 '6 inches flowing off. Deducting this from 8 inches, the amount left to percolate is 3 '4 inches, which DEEP- WELL WATERS 83 would yield, from an area of 422 square miles, 3,304,000,000 cubic feet per annum, or 56,000,000 gallons per day. But the whole of this water as it travels past the wells down the valley cannot be intercepted. "In the driest of three years, therefore, especially if it came to the last in the cycle, 56,000,000 would clearly not be obtainable, probably not more than 47,000,000, but we believe that the Companies, after providing reasonably for all below them, might, under the worst conditions, reckon on obtaining 40,000,000 gallons a day." Professor Boyd Dawkins believes that the body of the chalk contains such a store of water that it would equalise the rainfall, so that the amount available even during three consecutive dry years would be little short of that obtainable with an average rainfall. With this opinion the reporters disagree, since they consider that the only available water is in the fissures and crevices of the chalk, and that when these are drained the water held in the body of the chalk by capil- larity oozes out so slowly as to be practically useless. In the subjoined table are given the analyses of a number of public water supplies derived from deep wells in various strata. With one or two exceptions they are quite recent. Deep -well water differs little from spring water from the same geological source. An exception, however, occurs in certain districts where the chalk lies at a great depth beneath the London clay, and yields a very soft water containing carbonate and chloride of sodium. This is well adapted for domestic purposes, but not for use in high pressure boilers, nor for irrigation. Boilers in which it is used quickly leak, and the saline constituents have a prejudicial effect upon many forms of plant life. The utilisation of subterranean water obtained from bored wells is in many of our colonies converting deserts into fruit gardens, and rendering habitable large extents of country in which life was previously impossible on account of the scarcity of water (vide Chap. XVIII.). 8 4 WATER SUPPLIES . . 8 * s ^oo 3 e -^^H ^ " " H ~ ^ ~ p^^ ^ Q Q W Q - *pasu o 10 CO TJH , n co i*nc t 2 ^ Ul "w 1 3&vo K O W 1 : O O OS t^ ^c W o oT - l>- CO CN CM CN C^J CO CO ** O CO CO I 1 CO p 00 OS CO o I-H CO pop CO O l-^ O5 O CO ^ *% 1 >* g\ 2 6 J^ ' / __J^ jP O r 1 O 00 . O O O O (M ^ TJI O O i-l CO ' CO CN CO CN i CO co : Witham ,, 45 600 R.P.C. Mistley : Tendring Hundred W. W. Co. ... 05 160 J. C. Thresh. Braintree Public Supply Colchester(Donyland Brewery) '02 oo 430 305 T. A. Pooley. J. C. Thresh. Saffron Walden Public Supply 95 46 ? 5 Norwich .... 80 About 400 In none of the above examples is there any possibility of recent sewage contamination. Notwithstanding these facts the Rivers Pollution Com- missioners considered the total combined nitrogen to be an index of previous sewage contamination. They assumed that 100,000 parts of average London sewage contains 10 parts of combined nitrogen in solution. The mean amount of such nitrogen found in a large number of samples of rain waters examined was '032 per 100,000. After deducting this latter amount from the amount of nitrogen, in the form of nitrates, nitrites, and ammonia found in 100,000 parts of a potable water, the remainder, if any, they say, " represents the nitrogen derived from oxidised animal matters, with which the water has been in contact. Thus, a sample of water which contains, in the forms of nitrates, nitrites, and THE INTERPRETATION OF WATER ANALYSES 167 ammonia, '326 parts of nitrogen in 100,000 parts, has obtained 326 - '032 = -294 part of that nitrogen from animal matters. Now, this last amount of combined nitrogen is assumed to be contained in 2940 parts of average London sewage, and hence such a sample of water is said to exhibit 2940 parts of previous sewage or animal contamination in 100,000 parts." The Rivers Pollution Commissioners, how- ever, point out that, on the one hand, the nitrates may not indicate the full extent of the previous sewage pollution, since the roots of growing crops take up much of the ammonia, nitrites, and nitrates contained in polluted water, and animal matter which decomposes without access of air destroys nitrates ; and, on the other hand, that the nitrates present may indicate 10 per cent of previous sewage con- tamination in deep wells and springs, and the risk of using such waters be regarded as nil, providing surface pollution be rigidly excluded. This 10 per cent of previous sewage contamination corresponds to 1 grain of nitric nitrogen per gallon. Mr. F. Wallis Stoddart, in an excellent paper on " The Interpretation of the Results of Water Analysis," 1 describes a series of experiments in which he passed sewage containing cholera bacilli through a nitrifying bed of coarsely-powdered chalk, and found that although the organic matter in solution was completely nitrified, yet the cholera bacilli or spirilla could be detected in the effluent. From the result of his own observations and experiments, he concludes that natural waters " can at most obtain from one-tenth to two-tenths of a grain of nitrogen as nitrates per gallon from sources other than animal matter," and " that practically the whole of the nitrogen of sewage may be oxidised into nitric acid without materially diminishing the risk involved in drinking it." He urges that whenever the nitrogen as nitrates exceeds half a grain per gallon, it indicates "either dangerous proximity of the well to a source of pollution, or such easy communica- 1 Practitioner, 1893. 1 68 WATER SUPPLIES tion with it that the distance separating the two points is no guarantee of purification." In the various tables of analyses given in previous chapters will be found instances of many waters, the source of which I carefully examined, and which were collected and analysed by myself, containing more than this amount of nitric nitrogen ; and I am perfectly convinced that these waters are hygienically of the highest class, and can be used without the slightest risk or danger. On the other hand, in Table VII. there will be found analyses of many waters, containing very much less nitrogen as nitrates, which have almost certainly (in most cases the proof was very conclusive) given rise to outbreaks of typhoid fever. If Mr. Stoddart's maximum of '5 be accepted as proof that a water is dangerous, then the public and private water supplies of many of our healthiest districts districts remark- ably free from outbreaks of typhoid fever must all be con- sidered dangerous. As a matter of fact, the amount of nitrates which would condemn a water from one source may be absolutely without significance in water from another, all of which goes to demonstrate, as will be shown in the sequel, that mere chemical analysis is absolutely powerless to prove that any water is of such a quality as to be incapable of producing disease amongst those who drink it. Nitrites may result from the oxidation of ammonia, or from the reduction of nitrates, and, as it is an easily oxidisable compound, its presence indicates a condition of instability, of matter undergoing change. Usually this matter is of animal origin and derived from manure or sewage, the ammonia produced by their decomposition being in process of oxidation to nitrates. Where the soil is not sufficient in quantity, or is defective in quality, the oxidation may be incomplete, and incompletely purified and probably incompletely filtered water is the result. Usually in such cases an excessive amount of ammonia is also present. But, though usually, this is not invariably the source of the nitrites and ammonia. Where nitrates are present the nitric acid may be reduced by THE INTERPRETATION OF WATER ANALYSES 169 contact with rnetals, such as iron or lead, forming the pipes in which the water is conveyed, or lining the upper portion of the well. Where such is the case, a trace of the metal can always be detected in the water. Unless this fact be borne in mind and it often appears to be overlooked a good and wholesome water may be classed as dangerous or polluted. Certain organisms also found in water are capable of reducing nitrates to nitrites. Still the presence of nitrites always renders a water suspicious, and their origin should be carefully in- vestigated. Ammonia. All rain water contains this compound, as does also melted snow. The first portions of a shower, and the rain collected in the neighbourhood of towns, are richest in ammonia. As an average, *02 grain per gallon, taken by the Rivers Pollution Commissioners, is probably fairly approximate, but the variation is very wide ('2 to '01). In passing over or through the ground the ammonia is rapidly oxidised, and by the time the water reaches a stream or the general body of subsoil water, most .of it has disappeared. Rain water stored in covered cisterns, however, usually retains its ammonia for a considerable period. In such waters, therefore, the ammonia, unless excessive, is devoid of significance. Many deep -well waters also contain much ammonia, the origin of which has given rise to a good deal of surmise. The generally accepted theory is that it is due to the reducing action of ferruginous sands on the nitrates present. This may be so in some cases, but my observations lead me to believe that it is often due to the reduction of the nitrates by the metal of the bore tube, pump pipe, and lining of the well. I was led to this conclusion from the fact that I found the water from one and the same well, at one time quite free from ammonia, and at another containing as much as one part of ammonia per million parts of water. In the water containing ammonia I also found a very faint turbidity, which cleared up on the addition of a little acid, and gave the reactions for iron. The clear, ammonia-free water also, 170 WATER SUPPLIES when stored for a time in an iron tube became turbid, and nitrites, ammonia, and iron could be detected in it. Generally, however, the ammonia found in river, spring, and well waters is derived from putrescent animal matter that is, from manure and sewage ; but before this conclusion can be safely drawn, the other possible sources must be excluded. Dr. Brown, in his Report to the Massachusetts State Board of Health, 1892, whilst agreeing that imperfect oxidation of sewage matter is generally the source of the ammonia, calls attention to the fact that several waters in the State free from such pollution contain a considerable amount of free ammonia. "They are all associated with iron oxide and the fungus Crenothrix" Such waters are found also in many swampy regions, and in wells sunk in ferruginous river silt, and usually become turbid from the formation and deposition of oxide of iron when exposed to the air. The odour of these waters is said to be "often disagreeable from dissolved sulphuretted and carburetted hydrogen." Phosphates. Phosphatic minerals are widely distributed in nature, and traces may be dissolved by waters rich in carbonic acid. Albuminous matters, whether of vegetable or animal origin, give rise to phosphates by their decay, hence their presence, especially in what the analyst may conceive to be an excessive amount, has been held to indicate contamination. The difficulty of detecting phosphates, when silica is also present, as is usually the case, the still greater difficulty of estimating the quantity, and the very doubtful value of the information when obtained, has caused most chemists to ignore their presence. Traces may be found in wholesome waters, and their absence affords no proof that a water is free from pollution, hence the determination is useless. Organic Matter. By no known process can either the quantity or quality of the organic matter in water be deter- mined. When a known volume of water is evaporated to dryness, the weight of the residue is that of the inorganic and organic substances contained therein. When this residue is THE 1NTERPRETA7UON OF WATER ANALYSES 171 ignited the organic matter is destroyed and volatilised, and the " loss on ignition " has been regarded as approximately expressing the weight of the organic constituents. Such, however, is rarely the case, since carbonic acid may be driven off from the carbonates present, and any nitrates present will be more or less completely reduced. Moreover, some salts retain water so tenaciously that the whole is not driven off at the temperature used for drying, and this moisture is given off when the residue is ignited. For these reasons, chiefly, the " loss on ignition " cannot be depended upon as an index of the amount of organic matter present. But although the total amount of the animal and vegetable substances cannot be determined, the carbon and nitrogen therein can be ascer- tained by careful chemical analysis. Not only so, but the authors of the original process believed that, with certain reservations, the proportion of the nitrogen to carbon indicated whether the organic material was derived from the animal or vegetable kingdom. In fresh peaty water the Kivers Pollu- tion Commissioners found that N: = 1: 11 '93, whilst in similar waters, which had been stored for weeks or months in lakes, N:C = 1 : 5'92. After such water had been filtered through porous strata, N :C = 1 :3'26. In fresh sewage the average of a large number of samples gave N :C = 1 : 2*1. Highly polluted well waters, soakage from cesspools, etc., gave N : C = 1 : 3 '126. In sewage after filtration through soil the proportion of N to C rose from 1 : 1'8 to from 1 : 4'9 to 1 : 7'7. Evidently therefore the ratios of N to C "in soluble, vegetable, and animal organic matters vary in opposite directions during oxidation, a fact which renders more difficult the decision as to whether the organic matter present in any given sample of water is of animal or vegetable origin." All nitrogenous organic matter, whether of vegetable or animal origin, yields more or less ammonia when boiled with a strongly alkaline solution of permanganate of potash, and the ammonia so yielded by potable waters is called "albu- 172 WATER SUPPLIES rnenoid," or " organic " ammonia. The proportion of nitrogen in the ammonia so yielded to the total nitrogen in the organic matter is unfortunately not constant ; but the chemists to the Massachusetts Board of Health believe that when the process is performed as in their practice, about one -half of the nitrogen is converted into ammonia. Albumenoid substances of animal origin contain about 16 per cent of nitrogen, but vegetable matters contain very much less ; hence the amount of "albumenoid" ammonia is no index to the amount of organic matter present in the water. Professor Wanklyn, who devised this process, considers that undeniably contaminated waters always yield an excessive amount of albumenoid ammonia (over *10 part per million) ; usually with much free ammonia (over *OS part per million). If the albumenoid ammonia distils over very slowly and is in excess, but the water contains little free ammonia and very small quantities of chlorides, Professor Wanklyn considers this an indication that the contaminating matter is of vegetable origin. He adds : " The analytical characters, as brought out by the ammonia process, are very distinctive of good and bad waters, and are quite unmistakable." The generally accepted opinion, how- ever, is that no reliance can be placed upon these determinations taken alone, and in the Massachusetts State Board of Health Iteport for 1890 there is quoted as an example the results of the analyses of certain of the Boston water supplies. Reservoir No. 4 is known to contain the purest water, but the average " albumenoid ammonia " during two years was '26 per million. The water of the Mystic Lake is the worst of the Boston waters, since it contains both sewage and manufacturing refuse ; yet during the same period the average albumenoid ammonia was exactly the same as in the purer water. In the table given below many other examples will be found of the erroneous conclusions which may be drawn from a too implicit reliance upon the determination of the ammonia yielded by distillation with alkaline permanganate. Forschammer devised a process for the estimation of the THE INTERPRETATION OF WATER ANALYSES 173 amount of oxygen required to oxidise the organic matter in water. This method, as improved by the late Dr, Tidy, has become very popular, and many attempts have been made to render the results comparable with those obtained by Frank- land's process, in which the amount of organic carbon and nitrogen is ascertained by combustion, but with only partial success. The results, when compared with those obtained by the "albumenoid ammonia" process, prove that there is no relation between the amount of ammonia yielded by a water when distilled with an alkaline solution of permanganate of potash, and the amount of oxygen absorbed when the same water is digested with an acid solution of the same salt. This process tells us little or nothing of the nature of the polluting material ; it does not even distinguish between organic matter of vegetable and animal origin, and it affords us no evidence of the amount of such substances present. The presence of certain bodies of mineral origin (sulphuretted hydrogen, nitrites, the lower oxides of iron, etc.) also absorb oxygen, and unless great care is taken to ascertain the absence of these, or to ascertain the exact amount of oxygen consumed by them if present, serious errors may be introduced. When these corrections are made the oxygen process is still open to all the objections which have been urged against the albu- menoid ammonia process. It may condemn a perfectly harm- less water as polluted, and pass as of good quality a water of most dangerous character. The following table was devised by Drs. Tidy and Frankland. AMOUNT of OXYGEN absorbed by 1,000,000 parts of WATER. Upland Surface Water. Water other than Upland Surface Water. Water of great organic purity medium purity ,v , doubtful purity Impure water Not more tli an I'O 3-0 4-0 More than 4'0 Not more than '5 1-5 2-0 More than 2 '0 174 WATER SUPPLIES When the quality of a water is considered from the bio- logical side instead of the chemical, the absurdity of dividing waters into classes of pure, medium, doubtful purity, and impure, is obvious. A water containing a poisonous quantity of typhoid bacilli might upon analysis be brought within any of these classes, according to the quantity and quality of the accompanying impurities. In the analyses given below there are instances of waters coming within Tidy's limit of " great organic purity," yet which proved to be capable of causing disease. I have examined many such waters myself, and have also passed many waters as perfectly safe for domestic purposes which a mere reference to the above standards would have condemned as doubtful or impure. Many other special processes for determining whether a water be safe or dangerous have been devised, but inasmuch as they are rarely used, it may safely be inferred that they possess no advantage over those to which we have already referred. Whilst no single determination will enable the analyst to certify that a water is free from danger, or that it is so polluted as to be dangerous to health, the determination of several constituents may enable him to pronounce it to be polluted and dangerous, but will never justify him in certify- ing that it can be used absolutely without risk. As the freedom from all dangerous polluting material is the informa- tion usually sought from the analyst, it follows that if this cannot be ascertained by analysis, a chemical examination is in most cases quite useless. Where a water is known to be contaminated with sewage, or known to be liable to such pollution, an analysis is superfluous. When we also consider that many sources of supply are only subject to intermittent pollution, and that waters from the same reservoir or from the same well (vide Analyses Nos. 24, 25, and 26, 27) may vary considerably in composition, according to the depth from which the samples are taken, the character of the season, etc., it is obvious that the chemical examination of a water THE INTERPRETATION OF WATER ANALYSES 175 is a matter of comparatively trifling importance compared with the thorough examination of its source and an accurate knowledge of its history. Frequently waters are sent for analysis, and the analyst is wilfully kept in ignorance of their origin lest the information should prejudice his report, yet without this knowledge he is not justified in expressing an opinion whether any water can be used with safety. In commenting upon a recent paper in which I expressed these views, a writer in the Chemist and Druggist says : "It would seem, therefore, that we are face to face with the question, 'Is water analysis a failure.' It has been so exclusively the province of chemical analysts to pronounce judgment upon domestic waters, and they generally have given so little attention to the large issues attached to analysis, and so very much to sets of standard figures for chlorine, nitrogen, hardness, and so on, that the attack from the medical health side is not unexpected. There has been more wrangling over water analyses than over anything else in chemistry and for what ? Some figure in the second or third place of decimals, probably, and in regard to what this ammonia or that ammonia implies, when a visit to the source of the water and an inspection of the sewage trickling into it might settle everything. That is what Sir George Buchanan and Dr. Thresh advocate." The Royal Commission on Metropolitan Water Supply received evidence proving that waters containing very large amounts of organic matter were drunk continuously by a popula- tion with perfect impunity, whilst other waters containing so little organic matter as almost to defy chemical detection had proved, time after time, to be of the most poisonous character. For these reasons they conclude that the water question has passed from the domain of chemistry into that of biology. This, however, is not strictly correct. The biological problems involved in the investigation of water supplies are numerous and complex, and as yet but im- perfectly understood. At the present time it is doubtful 1 76 WATER SUPPLIES whether a biological examination really tells us more than a chemical analysis, and very often it cannot tell us as much. The reason will be explained shortly. Although a mere analysis cannot guarantee us purity and safety, yet it very frequently can reveal to us impurity and risk. When the source of a water, upon most careful examin- ation by an expert, is found to be free from all danger of pollution, and the chemical examination proves that the in- organic constituents are unobjectionable both in quantity and quality, and that organic matter is absent or present in barely appreciable amount, then safety, so far as human foresight can be trusted, may be guaranteed. If organic matter be present in appreciable quantity that is, if the water yield such a quantity of organic nitrogen and carbon, or albumenoid ammonia, or requires such an amount of permanganate for oxidation as to render it of suspicious or of doubtful purity a study of the history of the water and of its geological source may, and generally does, enable an opinion to be formed as to the nature of the organic matter, and as to whether it is of an innocuous or dangerous charac- ter. Chemical analysis, therefore, has its use ; it is only when it is made the sole arbiter between safety and risk that it is abused, and is liable to lead to errors fraught with most disastrous consequences. Let the analysis be as careful and complete as possible, but let the results always be inter- preted in the light afforded by a searching examination of the source of the sample. Let all so-called standards be abandoned as absurd, and let the opinion as to whether a water is dangerous or safe be based upon a full consideration of other and more important factors. In the following table the erroneous conclusions which may be deduced from a too great dependence upon analytical data are fully exemplified. THE INTERPRETATION OF WATER ANALYSES 177 Remarks. 1. Analysis of water from the river Ouse below where it receives the sewage of Buckingham. Examined for the Town Council, 29th February 1888, by W. W. Fisher, Public Analyst. Report " Does not appear from the analysis to contain sewage matters." Quoted by Dr. Parsons in his report to Local Government Board on an outbreak of enteric fever in 1888, as a "further illustration of the inability of a chemist to prove the quality of organic matter in water when its quantity is small." 2. Analysis of the Buckingham public water supply by Mr. Fisher. Certified by him to be a first-class water, yet believed by Dr. Parsons to have been the cause of the above outbreak. 3. Analysis of the Beverley water supply from borings in the chalk, by Mr. Baynes, 18th July 1884. In 1884 an outbreak of typhoid fever occurred here, and was investigated for the Local Government Board by Dr. Page. The evidence led him to conclude that the specific contamination of the water supply was the immediate cause of the out- break. The water had been repeatedly analysed, and the analysis given was made " on the very border of the period when the water was acting as the epidemic agent." It was certified to be "of a very high degree of purity, and eminently suitable for drinking and domestic purposes." Specifically infected sewage from an asylum had been spread upon land near the well and reservoir. 4. 5. Analyses of water from the much polluted Trent at (4) Torksey, and (5) Knaith, by Dr. Tidy, 20th December 1890. The analyst reported that "there is no evidence of the product of sewage contamina- tion." From Dr. Bruce Low's Report to the Local N 1 7 8 WATER SUPPLIES i s.moti f ui >asu uoSXxo O -* O5 CO CO p . CO .r^ . . CO - CO fc "ssr O CO t>- OO O5 i-H : AH /o o o : co e : : CO - (N O Oi : 05 c o^3 nH - - ^--- - - s THE INTERPRETATION OF WATER ANALYSES 179 rH O CO 1C O 1C O CO CO 10 .1^ 1 .^T t 'T fl 'rHO * COCNCNCOrH ^ CO O O rH CO O g : g '1 > J'S oS TS T5 JE ^ T^ O CO !>- a 3 o o c^^ O OW P 02 H rH (N CO r)5 O CO ,_| rHrH rH rHrHrHrHrH^(Nqi^| CO ! 8*3 O G rH Oi 00 l^ CO 05 1^- O CO O CO >< fc " I III S OO CO O O5 UTi ,2 p cp i_- cO >p OO 1O CO -^ l^ CO CO r-i . : o : : : : H rH rH rH P 1 > &, as ^2 00000 o 8 CO 1 O O O O O O o btf c oo~oooo o 8 ^oooSSo o 2 5 CO rH ** rH CO (M -* r-t CO rH rH rH o I 1 j i g o ' ' ' II ^ ' h w *& "n3 2 ' S Is .... o .b o dJ Jg ""^^ & ^ r r S aj .2 9 ?S r2^''i : ? ^I^IJI^ ^ Illll^l^ J^lSan 238 WATER SUPPLIES Table VIII. gives the area in acres, rapidity of filtration, etc., of the filter beds of several large public supplies, compiled from a report of a sub-committee of the Dumfries Town Council, which considered the subject with the view of improving their filtering arrangements. The River Commissioners on Metro- politan Water Supply reported that, as a general rule, the filtration of water by the London Companies was carried out efficiently, from 98 to 99 per cent of the organisms being removed from the water. The occasional failures, they thought, could be remedied by increasing the number of filter beds or by having recourse to double filtration ; " and assuming the water to be invariably as efficiently treated as it is usually by the most careful of the Companies, the raw waters of the Thames and Lea can be transformed, in the judgment of Dr. E. Frankland, who, as is well known, has been no sparing critic of the London water into a beverage quite as good, from the point of view of health, as deep- well water." This opinion, it must be remembered, is not shared by many other sanitarians of equal eminence. In any case it is obvious that only the efficiency of the filtration can safeguard the metropolis from outbreaks of typhoid fever and possibly of cholera. Doubtless, however, the Water Companies will not be slow to adopt the recommendation of the Commissioners, and will take every precaution suggested by the breakdown of the filtering arrangements at Altona. The area of filtering surface required is given by the formula A = =^ where Q is the maximum daily demand in cubic feet, F the filtering rate in feet, and A the required area in square feet. This area must always be available ; hence an additional area must be provided for use whilst other portions are being cleansed. According to Hennel the number of filter beds required for different populations is as under : PURIFICATION OF WATER ON LARGE SCALE 239 Population. 2,000 10,000 60,000 200,000 400,000 600,000 1,000,000 These include filter beds out of use for cleansing. In all cases a sufficient number of filter beds should be provided, to allow of the cleansing and renovating of one set without overworking the remainder. The filtration must not be too rapid, not over 2,000,000 gallons per acre daily. To accomplish this the head of water must be reduced after cleansing, and gradually increased as the pores of the sand become closed by the slimy matter which settles on its surface. By " filtering head " is meant the difference between the level of the water on the bed and in the well which receives the filtered water. After cleansing a few inches of head may be sufficient ; when it exceeds 3 feet the surface again requires renewal. Each bed should have an arrange- ment for regulating the flow, and the water should be admitted into the filter beds in such a manner as not to disturb the surface. The surface sand when removed for cleansing may be washed in hoppers admitting the \vater from below, or in troughs through which water is constantly flowing. Deep filter beds keep the water cooler in summer and retard freezing in winter, the latter being the more important, since freezing not only interferes with the efficiency of the filtration, but may damage the walls of the filter beds, by the expansion of the surface water in the act of freezing. In many places water is obtained from galleries or trenches sunk along the edge of lakes or running streams, the general impression being that the water so obtained is derived from the lake or stream, and that it undergoes a process of natural purification and filtration in its passage 240 WATER SUPPLIES through the intervening soil. In many cases, however, this is really ground water which is intercepted on its way to its natural outlet. Such water is usually very free from organic matter, and contains but few bacteria. Where the ground water falls below the level of the water in the stream or lake, doubtless a certain quantity of the water which passes into the galleries is derived from the latter sources, and is not so likely to be of good quality, since it only passes through soil which is constantly saturated with water, and therefore never aerated, and destitute of any oxidising powers. In such cases also the filtration is liable to be inefficient, and to allow of bacteria and other particulate matters passing into the collecting channels. Many attempts have been made to filter water on the large scale without employing filter beds, which are expensive not only on account of the space required, but of the con- stant labour and attention required to keep them in a state of efficiency. One of the best-known processes is that of the Atkins Filter and Engineering Company, which is in use by the Henley -on -Thames Water Company, and has been adopted by many large institutions. The filtering apparatus, technically known as the "Scrubber," consists of a perforated metal cylinder to contain the sand or other filtering material, fitted into a tank and so arranged as to revolve easily by turning a handle. The cylinder is only partly filled with the filtering material, and the collecting tubes, which convey away the filtered water, lie as nearly as possible in the centre of this as it lies in the cylinder. To clean the filter it is only necessary to turn the handle, when the cylinder revolves, agitating the filtering material with the water, and the latter, together with the impurities washed out, are run off through a by-pass. Several such "scrubbers" can be connected together. By another arrangement the sand is put into a number of discs fitted on a revolving centre collecting-tube. The water filters through the flat surface of each disc, so that the area of filtering surface is much increased. More perfect PURIFICATION OF WATER ON LARGE SCALE 241 filtration can be secured by passing the water through two "scrubbers" in succession, and affords, naturally, safer results for drinking water. The Company claims that, with an area of only 600 square feet, their machines will filter as much water as an acre of filter bed (3,000,000 gallons per day). Under the latter system the cost of cleansing is said to be from 5s. to 10s. per million gallons, whereas it is only about half the amount with the Atkin "scrubbers," with "the great sanitary improvement of daily cleansing in addition." Such machines for rapid filtration do not appear to be regarded with much favour in this country, and there are no records of the bacteriological examination of waters which have passed through these filters. The conditions laid down by the Massachusetts Board as being necessary for perfect filtration not being observed, experimental evidence of efficiency is much to be desired. Other machines of a similar character the "Loomis," the "Duplex," the "Hyatt," the "Bowden," etc. are, however, in use in the United States, chiefly for filter- ing turbid river-water, and Dr. P. S. Wales, Medical Director, United States Navy, states that, even with this rapid filtration, 98 per cent of the micro-organisms can be removed, but that "spores readily passed through the filtering material." (The typhoid and cholera bacilli are not known to form spores.) The four machines above referred to have been used for experimental purposes at the Museum of Hygiene, Washington, D.C., and gave very satis- factory results. The system of rapid filtration is successfully pursued, amongst other places, at Oakland, Cal., capacity for 24 hours . 4,000,000 gallons. Atlanta, Ga. ,, ,, . 3,000,000 Long Branch, N.Y. ,, ,, . 2,000,000 Ottnrawa, Iowa ,, ,, . 1,500,000 ,, Athol, Mass. ,, ,, . 1,000,000 ,, The city of Alleghany, Pa., was contemplating erecting a plant for filtering 30,000,000 gallons per day, when Dr. 242 WATER SUPPLIES Wales's paper was published. 1 These filters appear to be especially applicable for the waters of muddy, rapid rivers, which speedily clog the ordinary sand filter, and arrest the flow of water. To expedite the process of sedimentation so as to remove more of the suspended matter before passing the water into the filters, alum is largely used. The addition of about half a grain per gallon, on the average, is sufficient. At the Atlanta Waterworks, during 1890, 253 Ibs. of alum were used per day, corresponding to 617 grains per 1000 gallons. Some waters, such as that of the Potomac, cannot be clarified without a coagulant. In this country the water supply to the village of Ingatestone (Essex), previously referred to, derived from a fine sandy clay, for years resisted all our efforts to clarify it. Alum, or rather Spence's Alumino- ferric, was used as a coagulant, and the water then filtered through vertical sheets of flannel. This not proving satis- factory, various recently-introduced filtering and purifying materials were experimented with. Finally, at my recom- mendation, a filter bed was made of sand and polarite mixed in equal proportions, and with a few inches of fine sand on the top. This filter has now been in use for nearly two years, and has answered admirably. The use of the alum was discontinued, as it was found quite unnecessary. Two beds were prepared, so that one could be used whilst the other was cleansed and allowed to rest for re-aeration. At the Antwerp Waterworks, "spongy iron," together with gravel, was used as filtering material, but the beds choked up gradually and the iron became almost inactive. For three years, however, the results were satisfactory, so far as regards the purification of the water. To meet the difficulties just referred to, Dr. W. Anderson, F.R.S., invented the " Revolving Purifier," which has been in use at Antwerp since 1885, and has also been adopted at Boulogne-sur-Seine, Agra, Monte Video, and other places. The apparatus is described by the 1 Transactions of International Congress oj Hygiene, London, 1891. vol. vii. PURIFICATION OF WATER ON LARGE SCALE 243 inventor as a " cylinder supported horizontally on two hollow trunnions, of which one serves for the entrance and the other for the exit of the water. The cylinder contains a certain quantity of metallic iron, in the form either of cast-iron borings, or, preferably, of scrap iron, such as punchings from boiler plates. The cylinder is kept in continuous but slow rotation by any suitable means, the iron being continually lifted up and showered down through the passing water by a series of shelves or scoops fixed inside the shell of the cylinder. By this means the water, as it flows through, is brought thoroughly into contact with the charge of iron, which, in addition, by its constant motion and rubbing against itself and the sides of the cylinder, is kept always clean and active." During its passage through the apparatus the water takes up from ~j to i of a grain of iron per gallon, which is got rid of either by blowing in air or by allowing it to flow along shallow open troughs. The oxide thus, formed may settle in subsidence reservoirs, or may be filtered out by rapid passage through a thin layer of sand. At Boulogne the average amount of organic matter removed by this process from the Seine water was 63 per cent, and the microbes, which in the unfiltered water ranged from 800 to over 7000 per cubic centimetre, were reduced to an average of about 40. The bacteriological results are admittedly only approximate, and on one occasion, at least, a large number of bacteria were found in the filtrate. It seems probable that, compared with sand filtration as usually conducted, the revolving purifiers may destroy a larger proportion of the dissolved organic matter ; but unless supplemented by careful sand filtration it would be unsafe to assume that a specifically-polluted water could be rendered safe for drinking purposes by passing through one of these cylinders. Whilst sand is almost universally employed for the filtra- tion of water on the large scale, and usually is the sole effective filtering medium, in a few instances other materials have been used, together with the sand, either mixed there- 244 WATER SUPPLIES with, or in layers. A carbide of iron (Spence's Magnetic Car- bide) was in use for a large number of years for filtering the excessively-polluted Calder water for the domestic supply to Wakefield. This water was not only fouled by sewage, but also deeply discoloured by the refuse from dye-works ; yet the filters converted it into a colourless, palatable water. The layer of carbide was in use for nearly thirty years, and was never renewed ; all that was found to be required was the cleansing of the surface sand. The filtration was intermittent, to allow of the aeration of the filter. The magnetic carbide is also in use at Calcutta for filtering the turbid and polluted waters of the Hooghly, and at Cape Town, Demerara, and other places. Its use was discontinued at Wakefield because a purer supply has been obtained from another source. Spongy iron, polarite, and other insoluble iron compounds are used for similar purposes, and are useful in special cases, as in the examples given. Now that the removal of dissolved organic matter is considered to be of much less practical importance than the removal of the living organisms, less importance is being attached to the use of such materials, and it can only be under exceptional conditions that these aids to sand filtration are necessary. It is upon the proper use of sand that the real efficiency of filtration must depend, though where desirable this may be supplemented by the use of other filters, or the introduction of a layer or layers of other materials ; and the substances above enumerated, yielding nothing to the water, yet exerting an oxidising action upon the organic matter, are probably the best which have yet been discovered. At Reading Waterworks polarite is now largely used for filtering the water of the Kennet, a polluted, navigable stream. The following description of the filters is taken from an excellent paper read by Mr. Walter, the Waterworks Engineer, at a recent meeting of the County Association of Municipal Engineers held in Reading : "The process of purifying the river Kennet water is by PURIFICATION OF WATER ON LARGE SCALE 245 natural percolation, through a series of filters or chambers, the first chamber containing coke, and the second and third chambers * polarite,' granulated in two sizes ; there are also intermediate or regulating water chambers for facilitating cleaning out, the water passing from the last polarite chamber into a distributing channel, and on to sand filters, as it has been said, to make doubly sure of filtered water ; but sub- sequent experience has proved that perfect purification can be obtained by polarite chambers without the aid of sand. The first two sets of these chambers were started in work in November 1892. Each polarite chamber measures 40 feet by 9 feet, and has a depth of 2J feet of polarite, giving an area of 40 j^ards super each chamber, or a total of 160 yards super for the two sets. By adding the 2J feet of polarite in each set it gives a depth or thickness of 5 feet to each set of chambers, and an area of 80 yards super per set. From December 1892 to August 1893 there had passed through these two sets a total quantity of 409,880,000 gallons of water, giving an average of 18,848 gallons per yard super per day. Two additional sets were started in August last, 1893, of the same dimensions as the above, giving a total area of 160 yards super, with a depth of 5 feet for each set of chambers, which have passed on an average 12,500 gallons per yard super per day. From 1st January of the present year to the 31st of March last, 190,218,319 gallons of water have passed through these chambers, giving an average of 13,215 gallons per yard super per day, or at the rate of 550'6 gallons per yard super per hour. The water has been such that no complaints (which previously were an everyday occurrence) have been made since purification by polarite came into full working order. It has had a most severe test during the past and previous autumn and winter seasons, but like many a good engineer it has often been overworked, but has stood it well. From experience gained in connection with the treatment of the river Kennet water, there is no hesitation in stating the opinion that 'polarite,' 246 WATER SUPPLIES as applied here, is capable of effectually purifying a river water- supply for all purposes, and the system can be carried out at less cost of construction and maintenance than filtration by large areas of sand beds." The effluent from the polarite filters is afterwards passed through four sand filters, each having an area of 10,000 square feet. As these filters pass about 2,000,000 gallons per day, this is at the rate of over 8 gallons per square foot per hour, or four times the average of the London Water Companies. In connection with these works also there is an improved system of sand-washing, which was invented by Mr. Walker. Cone-shaped hoppers, mounted on trunnions, and connected at the bottom of the inverted cone with the water supply under pressure, are filled with the sand scrapings to be washed. The water is then turned on, and the upward rush keeps it in a continuous state of agitation, and the impurities are carried off by an outlet at the rim of the hopper. By this process sand -washing is not only less laborious, but less expensive than by the older methods. One man can wheel, tip, and wash 9 to 10 cubic yards of sand per day at a cost of 3|d. to 5d. per cubic yard. By the older processes the cost was from Is. 6d. to 3s. per cubic yard. Water, when softened by the addition of lime, also under- goes an improvement in quality, the precipitate of carbonate of lime carrying down with it a very large proportion of the microbes previously suspended in the water. The filtration through sand which follows, to remove the last trace of carbonate, still further purifies the water, so that the soften- ing process has a double advantage. As this process is primarily conducted for removing the carbonate of lime, and not for the removal of organic matter, and is of very considerable importance, it will be fully considered in a later chapter. CHAPTER XIV DOMESTIC PURIFICATION THE water supplied by a public company can scarcely be considered wholesome if it requires filtration by the consumer, yet in many towns unfiltered surface water is distributed, and as this often contains visible suspended impurities, some form of filtration must be resorted to if the water is to have a bright and pleasing appearance. The forms of filter generally employed for purifying all the water consumed in a dwelling may be classed under two heads (a) low-pressure filters, (6) high-pressure filters. The latter are directly in communication with the service pipe, and the water is filtered through under the pressure in the main ; whilst the former are indirectly connected by means of a ball-cock, the only pressure being the column of water in the filter above the filtering material. The high-pressure filters may contain any of the materials ordinarily used for clarifying water, either in a granular condition and tightly packed or in one porous mass. (Animal charcoal, polarite, magnetic carbide, carferal, silicated carbon, etc.) No doubt for a time such filters remove a considerable portion of the suspended matter, but they can never be trusted to remove more than a small portion of the bacteria, the most dangerous of the constituents. The separated filth accumulates, and to remove it there is usually an arrangement permitting of water being forced through in the opposite direction, whereby much of the dirt is washed away. All of 248 WATER SUPPLIES it cannot be thus removed; hence the efficiency of the filter is more or less rapidly impaired, and the filtering material requires constant renewal. Unfortunately, purchasers of such filters are rarely aware of this fact, or, if they are, the trouble and expense causes such renewals to take place at very long intervals. The whole system is wrong, and should not be FIG. 14. encouraged. Even if carefully attended to such filters cannot be depended upon for any length of time, and as they possess few advantages over low-pressure filters their use should be abandoned. The best filters of this class are Major Crease's, the Berkefeld and Pasteur filters. The former consists of a stout cylindrical vessel filled with carferal, a compound of iron, alumina, and carbon. The water passes in from the DOMESTIC PURIFICATION 249 main at one end, and out to supply the house from the opposite extremity. The filtering material within the cylinder is packed between two perforated plates, one of which can be screwed down upon the other so as to obtain any required degree of compression. It can also be readily unpacked for cleansing or for renewal of the carferal. The "Berkefeld" is, strictly speaking, a bacteriological filter, its object being, not the oxidation of dissolved organic matter, but the removal of the whole of the suspended matter, including the most minute organisms. The filtering cylinder is composed of compressed fossil earth (Kieselguhr), and the water is purified by filtration through the side. The suspended matters removed from the water remain upon the surface, and can easily be washed or brushed away, and the cylinders can be resterilised by being placed in warm water and boiled for an hour. Fig. 14 is a section of a cistern filter working with a pressure of 20 Ibs. upwards. A 3-tube filter of this kind will supply 50 gallons of water per hour. A smaller, single-tube filter is shown in Fig. 15. It is intended for attachment to the water supply either from a constant main service, with a pressure of, say, 30 Ibs. upwards, or from a cistern not less than 20 feet above where the filter is fixed. The Pasteur or Chamberland-Pasteur filter is very similar to the Berkefeld, but is made of china clay, is somewhat harder, and therefore not so readily fractured. Both are efficacious at first, but the latter is said to yield a more palatable filtrate. To the use of the Pasteur filter by the French army during recent years is attributed the great decrease in the mortality from typhoid fever amongst the soldiers (50 per cent). In other instances, when used for manufacturing purposes, their use has been discontinued on account of the slowness of the filtration, and because after prolonged use the filtered water was no longer bacteriological ly satisfactory. In a series of experiments made by Dr. Johnston, bacteria were found in the water passing through a Berkefeld filter within from 3 to 250 WATER SUPPLIES 10 days of continuous use. The Pasteur filtrate remained sterile for six weeks. Recent experiments made by Dr. Sims Woodhead (Brit. Med. Journal} confirm the superiority of the Pasteur filter. u FIG. 15. S. Water-inlet. T. Outlet for filtered water. U. Outlet for water used for washing cylinder. A number of forms of these high-pressure filters are made for fixing to taps, pumps, etc. They yield a water which at first is absolutely free from micro-organisms, and as they are extremely simple in construction and admit of being very easily cleansed, no other filter can be compared with them for high-pressure work. Bailey Denton's self -supplying filter may be taken as typical of the low-pressure service filter. The upper compartment contains the filtering material, which may be sand, charcoal, or any other of the substances used for such a purpose, and is fed from the house cistern at a higher level. When the filtered water in the tank below DOMESTIC PURIFICATION 251 reaches a certain level the supply to the filter is cut off, and the remaining water as it drains from the filtering material is replaced by air, so that the filter is frequently aerated. If fixed in an easily accessible situation, the material can be examined and removed for cleansing as often as may be required. The capacity of the lower compartment is made suitable for the actual requirements of the household. Kain water may be effectually filtered by some such arrangement as the above, and if for any reason the reservoir for the filtered water is below the level of the ground, the water may be raised by a pump. Even with this system of treatment the rain water should be collected by means of a "separator," in order to prevent an unnecessary amount of filth being passed into the storage cistern, which not only fouls the water but causes the filter to require much more frequent cleansing. The number of domestic filters in the market is enormous, and it may truthfully be asserted that the majority of them are worthless. Some are intended merely to remove a portion of the dissolved organic matter, and fail entirely to remove any bacteria which may be present. Others, which claim to remove the micro-organisms, only do this imperfectly and for a short time, and after being in use for a period the filtered water may actually contain more bacteria than were present in the unfiltered water. The use of such filters engenders a false feeling of security, and the users may fall victims to their misplaced confidence. I have had occasion to examine several much-vaunted filters, and found them absolutely useless ; they were coarse strainers and nothing more. The so-called " table filters " are usually the least reliable, since the amount of filtering material is too small to purify the water for any length of time, if at all ; and if the material be made sufficiently compact to prevent the passage of micro- organisms, the rate of filtration is excessively slow, and the pores of the filter become rapidly choked. The Berkefeld and Pasteur filters are probably the most reliable, but are very 2 5 2 WATER SUPPLIES slow in action. The tubes must be frequently removed, washed, first with water, then with a dilute solution of permanganate of potash, and finally sterilised by boiling or by heating over a charcoal stove or Bunsen burner. For ordinary domestic purposes an inexpensive sand filter, which can be made by any person, is as good, or better, than many of the high-priced filters in the market. The follow- FILTER PAPER FIG. 16. ing is a description of a cottage filter (Fig. 16) costing only a few pence : Take a large-sized earthenware flower-pot, and plug the hole at the bottom with a cork, through which passes a short piece of glass tube. Upon the bottom place a few fragments of a broken flower-pot (pieces \ to \ inch square). Upon these place a layer of small, clean- washed gravel, and upon this 6 to 1 2 inches of well- washed, fine, sharp sand. Cover the smooth surface of the sand with a circular piece of coarse filter DOMESTIC PURIFICATION 253 paper and sprinkle over this a few pieces of the small gravel. Mount the pot on a tripod or other convenient stand, and it is ready for use. The paper prevents the upper surface of the sand being disturbed by pouring in the water, and can be removed, together with most of the sediment which has formed thereon, as often as necessary. Every few months, or oftener if required, the sand can be thoroughly washed and replaced. A layer of finely -granulated polarite and sand, in equal quantities, may be substituted for the lower half of the sand layer, and improves the character of the filtered water in some instances, especially where the water to be filtered contains much vegetable organic matter, as is usually the case when taken from ponds. For the polarite, magnetic carbide, spongy iron, or animal charcoal may be substituted to suit particular circumstances. Animal char- coal, from the remarkable power which it possesses of removing certain colouring matters from water, and of absorbing or oxidising organic matters generally, of a complex character, used to be considered one of the best, if not the best, of all filtering materials. Water, however, which has been in con- tact with it forms a favourable medium for the growth of low forms of life, and bacteria grow within its pores. Prof. P. Frankland found that for some days animal charcoal removed most of the bacteria, but that it gradually lost this power, and before the end of a month the filtered water contained many more germs than the unfiltered. It will remove traces of lead, but this property it does not retain for any lengthened period. Vegetable charcoal, ground coke, and other forms of charcoal also are used as filtering media, but they do not possess the decolorising and oxidising powers of animal char- coal. They are equally efficacious in removing low forms of life, and retain this property longer. Ground slag, pumice, sandstone in slabs, etc., are occasionally employed in filters, but possess no advantage over good sand. Sponge soon becomes foul, and only acts as a coarse strainer ; its use is not recommended. 254 WATER SUPPLIES Whatever material be used, it must be remembered that it can only retain its efficiency for a limited period, and no filter should be purchased which does not permit of the filtering media being easily removed for cleansing or re- newal. The filter should also contain a sufficient amount of the material to produce something more than a mere straining action. If not of sufficient depth, it may remove all the coarser suspended matters, and the water appear bright, yet the micro-organisms may pass through with the utmost ease. Earthenware vessels are the best for containing the filtering medium. Galvanised iron is easily acted upon, and may contaminate the water with zinc. Wooden casks may be used if the inside has been previously well charred, and if the charring be repeated occasionally. When drinking water is of suspicious quality, and there is the slightest doubt about the efficiency of the filtration, it should be well boiled before use, say for ten minutes. This kills everything save certain very resistant spores; but as there are good grounds for believing that none of these spores are disease producing, their presence is of little consequence. It is better to use the water soon after cooling and before the spores have had time to develop. Boiling also removes most of the carbonates of lime and magnesia, rendering the water softer; as the dissolved gases are also given off, its taste is flat and insipid. It can easily be again aerated by pouring through a cullender or sieve from some little height, when the finely-divided streams of water again take up gases from the air. By distillation a pure water may be obtained from the sea, and from other salt -laden or impure waters. The saline matters remain behind in the boilers, and the steam, when condensed, can only contain any traces of volatile im- purities which may have been present. These volatile sub- stances have been charged with causing diarrhoea, but it is much more probable that the illness was due to defective distillation allowing some of the impure water to gain access DOMESTIC PURIFICATION 255 to the vessel in which the distilled water was being condensed or collected. By aeration the insipid flavour of distilled water may be improved. When tea or coffee is made with boiling water, the astrin- gent matter in the leaves or berries may tend to produce still further purification. In many epidemics of typhoid fever, it has been noticed that persons who drank the infected water only when made into tea or coffee escaped entirely. Turbid and polluted waters are sometimes clarified by the addition of from 2 to 6 grains of alum to each gallon, a very little lime also being added if precipitation is not sufficiently rapid. The flocculent precipitate which forms carries down with it most of the bacteria. Perchloride of iron is sometimes used instead of alum, and for the same purpose. Where only foul-smelling, impure water is obtainable, Dr. Parkes recommended the use of permanganate of potassium, which is the active ingredient in Condy's Fluid. The solu- tion of permanganate should be added gradually and with constant stirring, until a very faint but permanent pink tint is perceptible. A little alum is then added, and the water allowed to clear by subsidence. Such waters also are im- proved in quality by being stored in well -charred casks. Very foul waters, when kept, often undergo a kind of fermenta- tion, and become clear, bright, and palatable. CHAPTER XV THE SOFTENING OF HARD WATER As previously explained, the hardness of water is due to the presence of compounds of lime and magnesia, chiefly the former. The temporary hardness is due entirely to the carbonates of these bases, whilst the permanent hardness is caused by the sulphates, chlorides, and other salts. The disadvantages attending the use of hard waters have already been referred to, the chief being the waste of soap when the water is used for certain domestic purposes. With very hard waters this waste is so great that it is much more economical to soften the whole of a public supply than for each con- sumer to soften his quota by aid of soda or soap. From the description of the various processes^ in use for softening water, and their cost, the conditions which determine whether it is advisable to adopt one or other of them will be manifest. Water may be softened (a) by boiling; (b) by distillation; and (c) by the addition of lime, with or without carbonate of soda, soda ash, or other chemicals. (a) By boiling, the carbonic acid gas is driven off, and the carbonates of lime and magnesia which had been held in solution by this gas are deposited. The process is trouble- some and expensive. The Rivers Pollution Commissioners calculated that the fuel (coal) necessary to be used to soften 1000 gallons of water by boiling for half-an-hour would cost about 7s. 6d. The same quantity of Thames water softened THE SOFTENING OF HARD WATER . 257 by soap would cost 9s., so that boiling is not much less expensive than softening by soap. (6) Distillation naturally is much more expensive than simple boiling, and would never be resorted to simply for softening a water. Boiling merely removes the temporary hardness ; distillation separates all the saline ingredients, so that distilled water is the softest of all waters. (c) By the addition of lime. Lime has a great affinity for carbonic acid, combining therewith and forming carbonate of lime or chalk. When lime, therefore, is added to a natural water, the carbonic acid is absorbed, and the chalk previously held in solution thereby is precipitated, together with any carbonate of magnesia which may have been present. The sulphates and chlorides are unaffected, so that the permanent hardness is not reduced. Care has to be taken that an excess of lime be not added, since it is somewhat soluble in water, and any excess present will again increase the hard- ness. As 1 cwt. of lime, costing Is., will soften as much water as 2 cwts. of 60 per cent soda ash, costing 14s., or 1 ton of soap, costing over .30, there can be no question as to the economy of using lime. Dr. Clark was the original patentee of the lime process, and it is the one almost uni- versally adopted. Since the lapse of his patent many modifications have been devised for the purpose of dosing the water automatically with the proper quantity of lime, and for facilitating the removal of the carbonates precipi- tated. Atkins', Gittens', the Porter-Clark, the Stanhope, the Howatson, and Archbutt and Deeley's processes, are those best known, but some of these are more especially designed for softening water for manufacturing purposes and for use in steam boilers, than for water for domestic use. In Clark's original process lime water was added to the water to be treated, and the mixture was allowed to clear by subsidence in large tanks or reservoirs. To ensure com- plete clarification required at least 24 hours. Large tanks were necessary, and these had frequently to be cleansed. s 258 WATER SUPPLIES Modern inventors have devised means for dispensing with the large settling tanks, and for ensuring much more rapid and complete removal of the precipitated carbonates. In Atkins' process lime is mixed with water in a cylinder called the "lime cylinder," and the solution so formed passes through special regulating valves into a "mixer," in which it is mixed with the water to be treated in the proper pro- portion. The mixture then flows into a " softening cistern," in which a portion of the precipitated matter is deposited, and the partially clarified effluent is next conducted into patent machine filters, which " are constructed with a series of hollow metal discs, covered with cloth, so arranged as to give the largest possible amount of surface in the smallest space." Sets of revolving brushes are attached in such a manner as to play over the whole surface of the discs when set in motion, and by means of pulleys outside the tanks, worked if necessary by steam, the brushes are made to revolve, and the filters are rapidly cleansed. At Henley (population 5000) such an apparatus, with three filters, has been in use since 1882, and, according to Professor Attfield's analysis, the water is reduced by the treatment from 19*5 to 4*2 of hardness. At Southampton (population 65,000) about 2,000,000 gallons of water per day are softened, and the plant is said to be the largest in the world. It includes twelve filters, a softening tank 76 feet x 45 feet x 5| feet, two "lime" cylinders, mixer, and lime -slacking mill, all comprised in one building measuring about 134 feet by 48 feet. Without enlarging the building additional plant can be added, so as to increase the supply of softened water to 3,000,000 gallons per day. 1 At Lambeth Workhouse, with 1500 inmates, there is an installation for softening 300,000 1 Much dissatisfaction has arisen lately at Southampton in consequence of the water, after being softened, depositing calcareous matter in the mains, and not always being delivered free from turbidity. Whilst, on the one side, this is declared to be the fault of the process employed, the patentees assert that is entirely due to the careless way in which the system is worked. THE SOFTENING OF HARD WATER 259 gallons of water per day. The plant occupies a space of 22 feet by 16 feet, and the only attention required is said to be the labour of one man for an hour a day. The cost of the plant was about 2000, and the total expense of treating the water supply is said not to exceed 50 per year, or, including interest on capital, about Jd. per 1000 gallons. The saving in soap, soda, fuel for boilers, repairs to boilers, tea, etc., is believed to amount to over .1000 per year. The Atkins Company, recognising the validity of the objections to this system where comparatively small quantities of water are required, have recently introduced a plant dispensing with the costly machinery, and reducing the expense and trouble of cleaning and renewing the filters. The apparatus (Fig. 17) consists of three parts, viz. a "lime cylinder," B; a mixer, A; and a " softening cistern," D, holding two hours' supply. The mixture of lime and hard water is delivered at the bottom of the cistern, and the softened and clarified water flows over the top into troughs, which convey it into the storage cistern. The action is continuous. Mr. W. G. Atkins has also recently introduced a new form of filter, which is stated to be " capable of dealing with un- limited quantities of suspended matters, and in which the filter- ing medium is constantly being cleaned, sterilised and aerated." The Porter-Clark Company claim that their system is the most economical, since the apparatus is of a very simple character, requires very little labour and attention, and works under pressure, so that the softened and filtered water can be delivered into high-pressure cisterns without pumping. It consists of two vertical cylinders and a filter press. In the first cylinder there is a continuous preparation of lime water. In the second the hard water and proper proportion of lime water are mixed, and in the press, which is made up of a series of plates, with cloths interposed, the precipitate formed is filtered out. Where large quantities of water are being treated, some motive power is required to keep the contents of both cylinders in a state of agitation. The A / THE SOFTENING OF HARD WATER 261 approximate price of a plant softening, automatically, 1000 gallons an hour, is 200 ; for softening 2000 gallons, 280. The London and North- Western Railway Company use this system at various depots. At Liverpool, Camden, Willesden, and Rugby, about 1,000,000 gallons, in all, are softened daily for use in their locomotives. Modified forms of this apparatus are made for special purposes. One form, which dispenses with motive power, save that of a man for a few minutes daily, will soften from 500 to 2000 gallons of water per hour, and by the use of various other reagents besides lime, such as caustic soda and carbonate of soda, the permanent as well as the temporary hardness can be reduced where necessary. The Porter-Clark process has been adopted in a large number of public institutions, manufactories, mansions, etc. The " Stanhope " water softener (Fig. 18) occupies but little space, possesses no movable parts, and no filtering apparatus, the water being clarified by subsidence in special tanks con- taining numerous sloping shelves, upon which the carbonates are deposited. It aims at reducing both the permanent and temporary hardness, lime and soda being the chemicals used for this purpose. The only attendance required is that of a man to mix the lime-water and soda every few hours, and to open the mud cocks occasionally to let out the accumulated precipitate. The cost of softening by this process is stated by the makers to average Id. per 1000 gallons, though this will depend upon the character of the water treated. It appears to be a favourite with manufacturers, especially wool- washers and bleachers, and with large users of steam power for boiler purposes. Quite recently the Stanhope water .softeners and purifiers have been considerably improved. For the sloping shelves in the clarifying tower a series of perforated funnel-shaped cones (Fig. 19) have been substituted. These cause the water to traverse the tower more slowly, and more perfect sedimentation results, A continuous mechanical lime mixer has also been added. For potable purposes some system of filtration is necessary to secure absolute clearness. The FIG. 18. The "Stanhope ' Water Softener. THE SOFTENING OF HARD WATER 263 makers recommend filter presses, since the work left for the cloths to do is almost nil, and they may be used for a length of time without requiring cleaning. The natural head of water from the clarifying tower supplies all the pressure necessary. This simple mode of filtration may be sufficient for certain very pure waters, but for contaminated waters sand filtration would be far preferable. The " Howatson " softener is somewhat similar in principle to the above. The lower portion of the apparatus consists of a tank divided into two compartments, each having a hopper bottom. Into one the water and chemicals are introduced, and after chemical action has taken place the mixture passes at the bottom into the other, which acts as a "subsidence filter." The lime and other chemicals are contained in two smaller tanks placed above the larger, and which are used alternately. By means of floats, cocks, and nozzles, the proportions of the chemical solution and of the hard water to be softened can be regulated. No agitator is required, and the deposited carbonates are removed by occasionally turning the sludge taps at the bottom of the hoppers. At Stroud Waterworks the water is softened and clarified by a very simple modification of Clark's original process, all filtering machines being abandoned. By aid of a small water wheel, driven by the water to be treated, two pumps are worked, one raising lime water and the other the hard water. By altering the length of the stroke the proportion of the two can be adjusted, and as the rapidity with which the wheel rotates depends upon the pressure of the water in the mains, the relative quantities of lime water and hard water pumped remain constant. The treated water is clarified by subsidence in large settling tanks. The machine above referred to is the patent of C. E. Gittens, Limited, and will soften 1,000,000 gallons of water per day. 1 Messrs. Archbutt and Deeley have recently devised an apparatus which they regard as having many advantages 1 The amount actually softened is 300,000 gallons per day. FIG. 19. The Stanhope Water Softener (Clarifying Tower). THE SOFTENING OF HARD WATER 265 over others in the market, especially for treating waters containing magnesia salts. The chemicals used (lime and soda ash) are boiled with water and then mixed with the hard water, contained in a tank, by means of a steam " trajector." After thorough mixing, steam and air are forced by a " blower " through perforations in a series of pipes laid close to the bottom of the tank. This stirs up the mud and diffuses it throughout the water, and when the liquid is allowed to rest precipitation is very rapid. In from thirty minutes to one hour the water is almost perfectly clear and can be drawn off. By using duplicate tanks, one quantity of water can be treated whilst that in the other is undergoing clarification. Water which contains magnesia compounds, after precipitation, still contains a little carbonate of magnesia, which rapidly blocks up the boiler " injector." To obviate this the water, when being drawn off from the settling tank into the storage tank, is dosed with carbonic acid gas by aid of a blower. The carbonic acid is derived from the combus- tion of coke in a special stove. The water when sufficiently carbonated no longer deposits in the tubes. By this process the labour involved is as great for softening 2000 gallons as 20,000, but with large quantities the expense for labour is said not to exceed ^d. per 1000 gallons. Some waters are found to clarify much more rapidly if a little alum be added, together with the other chemicals, and this the inventors recommend in such cases. The cost for chemicals required to soften waters of various qualities is given in the following table by Messrs. Archbutt and Deeley, and is quoted here, since the chemicals used in this process are the same, both in quality and quantity, as those used in other processes which are designed to soften water containing both lime and magnesia. It will be observed that the cost increases rapidly with the amount of sulphates present, especially sulphate of magnesia, since such water can only be softened by use of soda ash as well as lime. In each case the hardness is reduced to from 3 to 5. 266 WATER SUPPLIES I O5 00 * CO l^ 1^ CO O Oi CO 1- r-l T . .CO O CO OJ 13 rH r-l ^ a 3 Tfi Ol r 1 >O CO O5 rH N Lj OO CO CO CO CO . .00 CO GO O ^ E^H oo CM b c. . . Tf . CO CO C- T3 P C CN 1^ tfl ' ' CO o :N c! l^. TO i i rH r-i 2'" n CO S^ a> ^ ' X 05 CO O5 rH O Ci CO t- TjH a, CO TTI t- r^ r-< ^ O O CN CN (M -CO rH rH d 04 s " & s O5 I O CO Irt CO CO CO ^N .1^ vn co o 01 O> . Is CO CO ^ti i I ' ' O o o ^ ^o i 1 CN g VO CO CO lO r-l CO -OS . CO r-l tO CO GO r-l . 4J O ^ CO rH ' ' Ci 1^ 10 r-l 3l 53 o ^ GO CD 1^ l^. l^ (M . . .CO ^1 00 10 ^ Jo OO 71 CO ' ' ' Oi rH rH 1 ^ ^ 4 s 1 1 c w S- Ss O so P 5 0/2 S - 5 "'"' g bO *^ ^ ^ rH .2 PC Pj >rH ^ *rH *pH -H O rH ^ p^ ^i ^3 "-- rH 3 NUMBE "S 5b'o bo So So ^5 111 11 | 8 o 1 THE SOFTENING OF HARD WATER 267 The Maignen "Filtre Rapide" Co. are the makers of a plant which softens and filters the water automatically. By means of a small motor worked by the flow of the water to be softened, the proper amount of " Anti-calcaire " is added, and mixture takes place in a small tank. From this the water flows to another tank, where most of the sedi- ment is deposited. Finally it traverses one of their rapid filters and reaches the storage tank in a completely clarified condition. Although certain of the processes described would appear to require very little personal attention, according to the statements of the inventors, yet, if uniformly satisfactory results are to be obtained, there must be constant supervision. The treated water must be repeatedly examined to ascertain that neither too little nor too much of the lime or other chemicals is being added. If too little, the water will not be properly softened, and if too much, the water will be rendered alkaline, and the magnesia will not be removed. When the amount of lime added is a little less than the theoretical quantity required to precipitate wholly the lime and magnesia salts, the two carbonates separate in a form which settles well, and the softened water filters readily. When the full theoretical amount is used, or a slight excess, the carbonates deposit slowly, and in a form which rapidly clogs the filters. Even after passing the filter, more magnesia continues to separate for from twelve to twenty-four hours. When spring or deep -well waters are being softened, the best proportions of lime water and spring or well water having been once determined, it only remains to examine the water occasionally to see that these proportions are being main- tained, and that the lime water is uniform in strength. If the lime water be not saturated with lime it will be too weak, whereas, if by undue agitation it is not only saturated, but contains lime in suspension, it will be too strong. With river waters the case is often different. The composition may vary considerably with the season, and, if a tidal river, 268 WATER SUPPLIES with the state of the tide, and skilled examinations must be frequently performed to ascertain the exact proportion of chemicals to be added. The Rivers Pollution Commissioners state that at Canter- bury, Caterham, and Tring, the water is reduced 20 in hardness by Clark's process, at a cost of only 27s. per 1,000,000 gallons for lime and labour. This may be taken as a fair estimate of the cost for lime and labour of softening an average sample of such hard waters as are being used for town supplies. Assuming that the interest of capital ex- pended in plant, buildings, land, etc., increases the cost to Id. per 1000 gallons, or 4:3: 4 per 1,000,000, and that the hardness to be reduced is only 16, the following may be taken as a low estimate of the saving effected by the soften- ing of a town water supply Cost of softening 1,000,000 gallons . . .434 Suppose T V only is used for washing purposes (domestic and laundry), and that half of this is softened with the cheapest soda, and the remainder with soap, the cost would be, very approximately ..... 60 Suppose ^ be used in steam boilers, that steam coal costs 13s. per ton, and that 25 per cent more fuel be used on account of incrustation, the cost of additional coal is 920 Total 69 2 This represents a saving of nearly 65 per 1,000,000 gallons, or of 23,000 a year to a town of 30,000 population. A town of one-third the size would save 7,000. Even in very small towns the saving would be enormous. This estimate is very much below those usually given by makers of softening apparatus, since in many cases the cost of softening is less than that given above, and a larger propor- tion of water may be used for washing purposes. They forget, however, that all the water used for washing purposes is not completely softened. When used for personal ablution THE SOFTENING OF HARD WATER 269 only the very small quantity taken up on the hands is completely softened, as the water after use is found to be only 1 to 2 degrees softer than before. The saving in the wear and tear of boilers, of culinary utensils, and the saving in the consumption of tea, are also items which have not been taken into account in the above estimate, yet which can be made to show a very considerable pecuniary balance in favour of softened water. Under the most adverse circumstances, where the water contains both lime and magnesia salts, and is "permanently" hard, requiring the use of soda as well as lime for softening, and large tanks and filter beds for ensuring complete clarification, the cost could not exceed Is. per 1000 gallons, and the saving effected would be actually greater than in the towns, where the cost was only Id., since the waste of soda, soap, fuel, etc., which would be prevented, would be so much greater in proportion. As few people realise the enormous saving effected by the substitution of a soft for a hard water supply, probably the following report, which deals not only with the actual economy in the use of soap, soda, and fuel, but also with the saving of labour and other items, will be read with interest. METROPOLITAN ASYLUMS BOARD. Report of the Committee for the Darenth Asylum ami Schools. ink May 1887. AT their meeting this day your Committee received from Mr. Harper, the Steward, a report as to the economical results which have attended the adoption at the Asylum and Schools of the Atkins system for softening the water supply. These results have fully justified the expectations of your Committee, inasmuch as, during the past twelve months, the estimated reduction in expenditure in the several departments of the Asylums and Schools, consequent upon the adoption of the system, has amounted to between 800 and 900,! an amount that may be subdivided as follows : 1 There being about 1800 inmates, the saving is at the rate of nearly 10s. per head per annum. A later report, dated 1892, confirms the above in every par- ticular. WA TER S UPPL IES Saving in value of soap and soda issued . . 300 Value of material and labour saved in replacing steam and hot- water pipes, circulating boilers, etc. . . . . . 384 Reduced annual wear and tear of steam boilers, circulating boilers . . . . 240 Saving of coal . . . . . . 5600 980 Deduct working expenses : Coat of lime . . . 38 17 Cost of renewing filter clotbs . 2000 Proportion of engineer's wages 50 108 17 Total estimated amount saved during the year 871 3 Regarding the reduction of expenditure on the items of soap and soda, the Steward points out that not only has an amount of 300 been saved during the past twelve months, but that the wear and tear on the linen has been greatly reduced by being washed in softened water, a fact which would indicate a considerable saving over and above the actual cost of washing materials used in the laundries. As to the reduction of expenditure on material and labour in re- placing steam and hot- water pipes, circulating boilers, etc., the Steward further points out that the steam boilers, which, before the introduction of the soft- water system, were incrusted with chalk deposit, are now in a most satisfactory condition, and give no trouble whatever. These boilers have, moreover, been recently examined by the inspector of the Engine Boiler Insurance Company, and from his report it would appear that not only is there now no incrustation, but tliat the incrusta- tion which had been left formerly and could not be removed, particularly in some inaccessible places, has come aivay of its own accord, leaving the boilers perfectly clean. This appears to your Committee to be an in- teresting point, and one to which attention should be specially directed. Regarding the condition of the circulating boilers, hot- water pipes, etc., which before were caked and congested with chalk deposit, it is satisfactory to be able to announce that this deposit has entirely disappeared, and that the coils and pipes are in every instance perfectly clean. The removal of these deposits indicates several distinct economies, inasmuch as (a) the circulating tanks, which it had before been found necessary to replace every year or two, will now, it is anticipated, last for several years ; (&) much less time, combined with a correspond- ing reduction in the consumption of fuel, is required to heat the water ; and (c) a higher temperature is maintained in the Wards and clscwlicrc than ivas before found practicable. (Signed) H. PRIVETT, Chairman, THE SOFTENING OF HARD WATER 271 The particular method of softening best adapted in any given case depends upon many circumstances, such as the character of the water to be softened, the purpose for which it is chiefly required, the amount of available space, the available motive power, the amount of water required, and whether for constant or occasional use. The cheapest plant, which, with the use of the cheapest chemicals, and the least expenditure in labour, will produce the desired result, will naturally be selected, and this can only be decided upon when all the above factors have been duly considered. Under suitable conditions all are capable of giving excellent results. During the process of softening, the bacteria contained in the water suffer a considerable decrease in number. Ap- parently these organisms become entangled in the precipitate formed, and settle therewith to the bottom of the tanks. Professor P. Frankland found that by agitating water with powdered chalk, the treated water after subsidence only contained about 3 per cent of the organisms originally present. A carefully-filtered softened water, therefore, ought to be 'practically sterile. With waters of a high degree of purity, the filtration necessary after softening would be merely to remove suspended particles of carbonates ; but where river water, known to be sewage contaminated, is being treated, the filtration must aim at removing all the micro-organisms which may have escaped precipitation, or have passed through the rapid filters supplied with certain of the machines that is, this rough filtration must be sup- plemented by thorough filtration through properly-prepared sand filters. A water which has been thus treated would appear to be as safe for domestic purposes as our present scientific knowledge enables us to make it, CHAPTEE XVI QUANTITY OF WATER REQUIRED FOR DOMESTIC AND OTHER PURPOSES THE amount of water necessary to supply all the wants of a given population may be calculated upon the basis of the theoretical requirements of each individual or household, plus the estimated quantity which will be necessary for municipal and manufacturing purposes, or it may be calculated upon the basis of the amount actually supplied to other similar communities. The results so obtained will often be found to vary considerably, and the causes of such variation are very difficult to explain. The amount used in households similarly circumstanced with reference to their supply varies greatly, according to the habits of the individual members ; but where the supply is practically unlimited and readily available, the quantity used is always greatly in excess of that consumed where the supply is limited, or where it is more or less difficult to obtain. In rural districts, where water has to be purchased from the hawker or fetched from a considerable distance, the amount used is astonishingly small, that which has been used for the purposes of personal ablution having often to serve afterwards for washing the crockery, and finally for washing the floors, etc. In numbers of cases I have found that the amount used in country cottages could not have greatly exceeded 1 gallon per person per day. Of course neither perfect cleanliness nor health is possible under such circum- WATER REQUIRED FOR DOMESTIC PURPOSES 273 stances. On the other hand, where the supply is abundant and easy of access, a very large proportion is often wasted, and 100 gallons or more per person per day may pass from the mains into the sewers. The purposes for which water is required may be summarised as follows (a) For drinking, either as water or made into such beverages as tea, coffee, and cocoa, and for cooking purposes ; (b) for personal ablution, including baths ; (c) for household washing, including cleansing and swilling of floors, yards, etc. ; (d) for use in water-closets ; (e) for the supply of horses, cattle, and washing of carriages ; (/) for watering plants and gardens in the dry season ; (g) for municipal purposes, cleansing streets, flushing sewers, extinguishing fires, etc. ; and (h) for manufacturing and trade purposes. Where, for municipal and manufacturing purposes, water can be more cheaply obtained from wells, streams, or other sources, obviously the public supply of pure water needs not be nearly so large as in towns where such sources are not available. Where subsoil water can readily be obtained from shallow wells, it may be utilised for many of the above purposes, especially for the stable and garden, and the demand upon the public supply be further curtailed. The amount of water required for each of the above purposes has been variously estimated. Professor Rankine, in his work on Civil Engineering, states as his opinion that 10 gallons per head should be allowed for domestic purposes, 10 gallons for municipal purposes, and 10 gallons for trade purposes in manufacturing towns. Most engineers, however, consider the estimate for municipal purposes to be too high, since in the majority of towns the amount used does not exceed 3 gallons per head. For trade purposes also Rankine's estimate is probably excessive, 7 gallons per head being a liberal allowance. Dr. Parkes 1 measured the water expended in several cases ; the following was the amount used by a man in the middle class, who may be taken as a fair type of a cleanly man belonging to a fairly clean household : 1 Parkes' Practical Hygiene. 274 WATER SUPPLIES Gallons daily per one Person. Cooking ........ '75 Fluid as drink (water, tea, coffee) .... '33 Ablution, including a daily sponge bath, which took 2 to 3 gallons ...... 5'0 Share of utensil and house washing . . . 3*0 Share of clothes (laundry) washing, estimated . 3*0 12-0 The above may be taken as a liberal estimate for domestic requirements applicable for most communities. Where water- closets are introduced, 2 to 6 gallons, according to the mode of flushing, must be allowed ; for the supply of horses and cattle and use in garden 2 to 5 gallons ; for municipal purposes to 10 gallons; and for manufacturing purposes to 10 gallons. Where the water is not required for trade or muni- cipal purposes, a supply of from 16 to 23 gallons per head will suffice ; but where the water is also wanted for cleansing streets, flushing sewers, supplying factories, etc., as much as 40 gallons may have to be provided. Allowing 2 gallons for unavoidable waste, we may take 18 gallons as the minimum and 42 as the maximum supply required by any community. These figures may be checked by the actual amounts used in various towns. The River Pollution Commissioners, in their Six.th Report, in discussing the question whether a constant or intermittent supply be the more economical, give two tables one of the amount of water supplied per house in each of seventy-one towns with a constant supply, and the other of twenty-four towns each having an intermittent supply. The following is a brief summary of the tables referred to : Constant Intermittent Supply. Supply. No. of towns using not more than 50 galls. per house ...... 3 1 No. of towns using over 50 and not more than 75 galls, per house ... 13 4 No. of towns using over 75 and not more than 100 galls, per house ... 8 2 WATER REQUIRED FOR DOMESTIC PURPOSES 275 Constant Intermittent Supply. Supply. No. of towns using over 100 and not more than 150 galls, per house ... 20 9 No. of towns using over 150 and not more than 200 galls, per house *. 10 2 No. of towns using over 200 and not more than 300 galls, per house . . . 12 4 No. of towns using over 300 and not more than 400 galls, per house ... 2 2 No. of towns using over 400 galls, per house 3 The mean daily supply per house in the seventy-one towns was 135 gallons, in the twenty-four towns 127 gallons. Taking five as the average number of persons per house, the mean daily supply under the constant system was 27 gallons, and under the intermittent system 25*4 gallons. In London, with an intermittent system of supply, the average per person was 40 gallons (204 per house). The amount of water supplied per house under both systems varied enormously. With a constant supply Hey- wood and Middlesborough furnished the two extremes. At the former town, with 5200 houses and 30 factories, only 20 gallons per house per day were consumed ; at the latter, with 7000 houses and 80 factories, the amount was 700 gallons, or thirty-five times as much. The quantity stated to be supplied to Heywood is probably erroneous, since the Heywood and Middleton Company is elsewhere mentioned as supplying 7000 houses and 150 manufactories with 100 gallons per house daily. This latter amount is, however, only one-seventh that of the Middlesborough supply, and the difference is the more marked inasmuch as both places are supplied by private companies, and the latter in each instance are reported to have inspectors who examine the taps and fittings to prevent waste. With an intermittent supply, Huddersfield, with its 8500 houses and 600 factories, only used 49 gallons per house daily, whilst Berwick, with 1150 houses and 7 factories, used 330 gallons per house. That these enormous differences 276 WATER SUPPLIES depend more upon the amount wasted than upon the amount used for either domestic, municipal, or trade purposes is almost certain. The consideration of a few more modern statistics confirms this opinion. In the following table the amount of water used daily per unit of population in a number of representative towns is given. Most of the figures are taken from recent reports of Medical Officers of Health or Water Companies. Population. Saffron Walden . . . 6,108 Melrose . . . . 1,300 Bridlington .... 9,806 Halstead . . . . 6,100 Chepstow . . . .3,387 East Ham .... 33,000 Atherstone . . . .5,000 St. Austell . . . . 3,400 Chelmsford .... 11,079 Bristol. . '. . . 222,000 Bedford .... 28,023 Weston-super-Mare . . 15,869 Swansea .... 93,864 Barking . . . .15,115 Nottingham. . . . 211,984 Wolverliampton . . . 82,620 Grantham . . . 16,746 Yeovil 9,648 Walthamstow . . . 49,400 The variations here, though not nearly so great as in the River Pollution Commissioners' table, are still very considerable. Having recently to make an examination of the Halstead supply, I verified the above figures. The supply there is constant, and the water is used for flushing sewers, watering the streets, etc., as well as for flushing water-closets, and other domestic purposes. In this town a large proportion of the women are engaged during the week at the crape factories, and Saturday is the great washing-day. The amount used on a Saturday was as under : WATER REQUIRED FOR DOMESTIC PURPOSES 277 From 8 A.M. to 2 P.M. . . . 9800 gallons per hour. ,, 2 P.M. to 4 P.M. . . . 9500 ,, i P.M. tO 5 P.M. . . . 6000 ,, ,, The average amount used on a week-day was 104,000 gallons, and on Sundays 84,000 gallons. Small as this amount appears, there is no doubt that a considerable portion was wasted, since many thousands of gallons passed from the service reservoir during the night, when little or none was being used. At Wolverharnpton the careful records kept at the Cor- poration Waterworks show that in 1868 "the domestic consumption per head of consumers, deducting for trade purposes, street watering, etc.," was 18 gallons. In 1892 it had increased to about 23 gallons. In the latter year the total amount supplied for all purposes was about 29 gallons per head daily. At Newcastle the consumption per head, for all purposes, in 1863 was 28 gallons; in 1881 it had increased to 38^ gallons. " This," says Dr. Armstrong, the Medical Officer of Health, "shows an increase of 37 per cent in the amount consumed for each person, due, no doubt, largely to improved habits of cleanliness among the people. Looking at the fact that baths and water-closets, which even then were considered as luxuries, are now regarded as necessities in almost every house of any pretensions to comfort, . . . it is not too much to assume that there will be a still further increase in the consumption per head." No doubt this in a measure is true, but it is at least probable that much of this increased consumption is really increased waste, consequent upon the increased age of the mains and fittings. In London, by greater attention to the sources of waste, the net supply per head of population has in many cases been very consider- ably decreased. The following table l is interesting as show- ing the actual amount of water supplied daily by the London Companies and the wide difference in the supply per head. 1 Report of Royal Commission on Metropolitan Water Supply, 1893. 27 8 WATER SUPPLIES Name of Company. Net Supply daily. Population. Net Supply per Head. New River .... 32,640,976 1,159,260 28-16 East London 39,704,601 1,158,500 34-27 Chelsea .... 9,557,388 287,362 33-25 West Middlesex . 15,419,907 577,235 26-71 Grand Junction 16,701,734 350,000 47-72 Lambeth .... 20,234,560 655,921 30-85 Sonthwark and Vauxhall 24,373,348 841,989 28-94 Kent ..... 12,530,891 460,524 27-21 171,163,385 5,490,791 31-19 Of this quantity it is estimated that about 20 per cent, or between 6 and 7 gallons per head, is used for trade and municipal purposes. Whilst the West Middlesex Company supply only 27 gallons per head, the Grand Junction Company supply 48 gallons, and this the engineer of the latter company explained to be chiefly due to waste, since they found it cheaper to pump water than to supervise and control the waste. The following table is taken from a paper by Mr. T. Duncanson, A.M.I.C.E., on "The Distribution of Water Supplies," read before the Liverpool Engineering Society, April 1894. Name of Company or Town. Year. Domestic Supply in Gallons per Head. Trade and Public Supplies. Gallons per Head. Total Gallons per Head. Percent- age of Supply. Given Constant. Liverpool Bradford 1893 1891 17-10 18 to 20 9-8 20-0 26-9 38 to 40 100 100 Manchester 1893 15-0 9-0 24-0 100' Birmingham . 1893 17-0 875 25-75 100 Glasgow . 1893 36-0 16-0 52-0 100 St. Helens 1893 18 to 21 1 8 to 20 36 to 41 100 Swansea . 1893 23-4 4-2 27-6 32 All waste is included in the amount set clown for domestic supply. WATER REQUIRED FOR DOMESTIC PURPOSES 279 Waste of water arises from two distinct groups of causes (a) those over which the consumer has no control, and (b) those under the control of the consumer. As a rule the latter causes are responsible for the larger portion of the waste. Under (a) are included leakages from faulty mains and service pipes, and all other hidden defects, where the water escapes unperceived into drains and sewers or into the subsoil ; under (b) the waste from defective house fittings, leaving taps open, etc. Such waste is also supplemented by an unnecessarily great consumption, due to the use of im- perfect appliances, such as many forms of closet basin, and flushing tanks, the automatic flushing of urinals, and to the use of water for gardens, fountains, and similar purposes. By the employment of a staff of inspectors the waste arising under (b) may be in a great measure controlled, but something more is required for the discovery and check of that arising under (a). By the use of water-waste meters or detectors the particular branch mains from which the water is escaping can be discovered, and by the aid of an instru- ment resembling a large stethoscope the faults can be local- ised. The " Deacon," " Tyler," " Kennedy," and " Ginman " waste detectors are those best known. These meters register automatically and continuously the rate at which the water is passing through the mains to which they are attached. It can thus be ascertained whether the draught has been excessive at any particular time, or whether this is constantly high. The number of houses supplied through each meter being known, it is easy to decide whether the amount of water which has passed is in excess of their requirements. If, after an examination of the fittings and rectification of visible defects, waste still continues, the mains and service pipes require attention. If the ear be applied to the service pipes near where they emerge from the ground, any escape of water from the pipe or main in the immediate neighbour- hood can be heard, the more distinctly the nearer the defect. The ear can also be applied to the uncovered main for a 280 WATER SUPPLIES similar purpose, but it is often more convenient to apply it indirectly, using a walking-stick or a special instrument. Upon placing one end on the exposed main and the other to the ear, the fault, if any, can be localised. Mr. E. Collins, M.I.C.E., in a paper recently read before the Institution of Civil Engineers, on " The Prevention and Detection of Waste of Water," says that a 4-inch Deacon's meter will control 400 to 500 houses, but that smaller districts are preferable. The outlay involved is consider- able, averaging 150 for each 1000 houses controlled. This sum includes the cost of the meters and of fixing them on a by-pass, and of the valves necessary for isolating the divisions of the district. Where the meters are in use, however, a much smaller staff of inspectors is necessary, since a glance at the meters enables the inspector to discover the locality in which waste is taking place. At Shoreditch, as previously mentioned, Mr. Collins was able in three years to so reduce the waste as to save annually 720,000,000 gallons of water. This was effected by a capital outlay of .1800, and an annual expenditure of 926 for staff and establish - mental expenses. Each 1,000,000 gallons saved cost there- fore about 1 : 9s. Small as this sum appears, it is probable that it exceeds the cost of pumping, especially if the most modern machinery be employed. The prevention of waste can only be accomplished by the expenditure of money, and whether it be more economical to allow the waste to continue or to control it depends upon circumstances varying from place to place, and it is only after a careful consideration of these that it can be determined in any given district which is the cheaper. When inquiries are made to ascertain the cause of the variation in the amount supplied in different towns, it is found that only on the assumption that it is due to the varying quantity wasted can an explanation be offered. Some towns, with manufactories using large quantities of water, use less in proportion to the population than others WATER REQUIRED FOR DOMESTIC PURPOSES 281 in which there are few or no manufactories. Towns in which there are very few water-closets often use more than towns in which water-closets are universal. Where the closets are chiefly flushed by hand more water may be used than where all have got a supply laid on. Where no water is used for sewer cleansing more is often used than where flushing arrangements are fixed at the end of every sewer. Where water from the mains is used for street cleansing and road watering, less is often actually used than in towns which obtain water for these purposes from other sources. In every town, moreover, there is a great outcry about the amount wasted, and we can only conclude therefore that since no other factor or combination of factors will explain the difference in the amount supplied per head daily, that this must be attributed chiefly to waste. Such being the case it is evident that the amount of water necessary for the supply of a town is very much less than the estimates given. Probably 20 gallons per head daily would be an abund- ant supply for all purposes in the majority of cases, and 30 gallons only be required in exceptional instances. To prevent waste and unnecessary consumption, however, so that the above quantities may suffice, the whole of the works in the first instance would have to be most carefully constructed, means taken to quickly detect where waste is occurring, constant supervision exercised over all house fit- tings, and all undue consumption checked by byelaws, or by insisting upon the use of water meters by large con- sumers. 1 Few persons realise the immense amount of water which is wasted in almost every town. Thus in Liverpool, where the average amount supplied daily per head was 33'5 gallons, Deacon's water-waste detectors were introduced, and these, together with efficient inspection, reduced the supply to 23 gallons without any restrictions being placed upon the consumers. At Shoreditch, with a population of 87,000, 1 A meter suitable for small consumers is a want yet to be supplied. 282 WATER SUPPLIES the introduction of waste detectors effected in the course of three years a diminution of waste and undue consumption amounting to 720,000,000 gallons per annum, or 23 gallons per head daily. Mr. Boulnois recommended the use of Deacon's meters at Exeter, and their introduction reduced the waste from 75 to 12 gallons per head per day. In other parts of London, in Bradford and elsewhere, where waste detectors have been introduced, the expenditure of water has been reduced by from one-third to one-half. A most instructive instance of what can be done by checking waste was given by Mr. Hawksley in evidence before the River Pollution Commission. He said that when "the city of Norwich Waterworks \vere transferred from a very old-fashioned company to a new one . . . the delivery amounted to 40 gallons per head per diem, and that amount of consumption exhausted all their pumping power. They obtained a very good manager, and, under my advice, they applied for an additional Act of Parliament to enable them to correct the fittings. . . . The bill was carried, and it was put into operation, and now and for many years past, although the constant supply has "been unfailingly in use, the water is never shut off, and the consumption has descended to 15 gallons per head per diem, as compared with 40 previously." In many cases a check is placed upon waste by placing in the service pipe leading to the house cistern a disc with a small hole in it, which prevents more than a certain amount of water passing through in a day. This, however, is a most objectionable arrange- ment, and quite unnecessary, since better results are obtained by adopting regulations as to the strength, proportion, and quality of the fittings, and enforcing the regulations. In tropical climates*, doubtless, the demand for water is greater, and probably even 30 gallons per head per day would be barely sufficient. In Bombay 40 gallons is sup- plied, and in Calcutta 35 '4 gallons of filtered water and 8 '9 gallons of unfiltered, total 44'3 gallons ; but in many other WATER REQUIRED FOR DOMESTIC PURPOSES 283 cities the amount used falls far short of this. In Madras, for instance, only about 18 gallons is supplied; but this is very probably far too little for all the requirements of the population. The amount of water required by various animals natur- ally varies, chiefly with the size. Cavalry horses are allowed 8 gallons, and artillery horses 10 gallons per day. Elephants require at least 25 gallons, camels 10 gallons, and oxen 6 gallons per head daily. By a careful study of the requirements of any community the amount of water which must be supplied daily may be estimated with a fair approach to accuracy ; but whilst every care is taken to avoid waste, it must be remembered that this cannot be entirely prevented, and that it is far wiser to provide a supply in excess of the requirements, so as to be prepared for contingencies, and for a possible increase in the demand, from growth of population and other causes. The amount of water used per week throughout the year does not vary greatly, but, as a rule, more water passes through the mains in summer than in winter. In Liverpool, during 1893, 1 the maximum consumption took place in the week ending 8th July, and was about 15 per cent above the average, and the minimum during March, November, and December, and was about 9 per cent below the average. (Vide Chapter XX.) In small towns and rural districts where a large number of houses have, gardens attached, the summer consumption of water is often greatly in excess of that used in winter. The most stringently enforced regulations often fail to prevent water being used in excess for gardening purposes during seasons of drought, and such misuse of the water by persons living in the lower portions of a district may deprive those residing upon higher ground of the supply to which they have an equal right. 1 Duncanson, loc. cit. CHAPTEE XVII SELECTION OF SOURCES OF WATER SUPPLY AND AMOUNT AVAILABLE FROM DIFFERENT SOURCES WHERE there is only one source of water available there is no question of selection, since there is no choice. Such instances, however, are comparatively rare : usually there are more sources than one from which water can be obtained; and in deciding upon one or another many points have to be considered. A water seriously contaminated with sewage or intermittently liable to such contamination, water con- taining mineral matter in excessive quantity or of deleterious quality, and water with any marked odour or colour, would naturally be at once rejected. Cceteris paribus, the water of greatest hygienic purity and best adapted for manu- facturing purposes would be selected. Where the available quantity or economy in utilisation, or both, are in favour of a water from a certain source, the importance of these factors must not be allowed to outweigh those of purity and freedom from risk. As the characteristics of good drinking waters and the dangers attendant upon the use of polluted waters have already been discussed, it is not necessary to do more than refer to them here, special attention being directed to the sections dealing with river water, the self-purification of rivers, and the discussion of the risks involved in the utilisation of river waters admittedly polluted, even when the intake is many miles below the source of pollution and SOURCES OF WATER SUPPLY, ETC. 285 the filtration is conducted according to most modern methods. Where towns of any magnitude are concerned the subject is so important that the services of experts engineering, medical, and chemical would naturally be enlisted; and by these all the advantages and disadvantages of the different available sources would be carefully considered, and the decision arrived at would be based upon the facts recorded and the opinions expressed in their reports. The nature of much of this evidence may be inferred from the sections treating of the quantity and quality of water obtainable from various sources, since the information there given is of general application. The estimates of cost of collecting, storing, and distributing will vary in each individual case, and certain points bearing upon these questions will now be briefly considered. In the first instance, however, it will be better to consider the simplest case that of providing a supply of water for a single house or small group of houses. In this, as in undertakings of greater magnitude, some knowledge of the geology of the district is in most cases absolutely necessary. Without this the search for underground water is mere groping in the dark, which may or may not be successful. Where a spring, however, is available, doubtless this will be at once selected, especially if it arises at such an elevation as to be capable of supplying the house or houses by gravitation. In examining any district for the discovery of springs, the sides of all streams should be carefully examined, and all tributary rivulets should be followed up to their respective sources. If the flow of the stream appears to be considerably augmented at any point, it is probably due to the influx of water from a spring, which may permit of being tapped above the point of discharge. In this case the con- struction of a reservoir large enough to hold at least a day's supply and the laying of a service main is all that is required. One great mistake is, however, frequently made in this simple arrangement. The pipe is rarely of sufficient size, and some- 286 WATER SUPPLIES times is not of suitable material. Galvanised iron pipe of 1 inch or even less diameter is often employed to convey water considerable distances. If the water contain little or no car- bonate of lime, the zinc will almost certainly be dissolved and contaminate the water. The pipe then becomes coated with a deposit of iron oxide, which tends continually to increase, and ultimately the calibre of the tube becomes too small to convey the required quantity of water. I have known many cases in which such pipes have had to be taken up and larger ones substituted. Cast-iron pipes coated inside with Angus Smith's protective varnish should be used, and the diameter should never be less than 2 inches. Where water is required for fire -extinguishing purposes also, the diameter of the pipe must be consider- ably greater, and the reservoir must be much larger. The size of main required under different circumstances will be discussed when the "distribution of water" is being considered. The character of the water yielded by springs from different geological formations has been discussed in Chapter V., and the variable yield from certain springs was also re- ferred to. Before attempting to utilise any spring as a source of water supply evidence should be obtained proving that even after periods of continued drought the yield is suffi- cient for the purposes required. Many springs which flow freely in the late winter, spring, and summer fail com- pletely in the autumn, or at least yield a greatly diminished supply. The evidence of people who may have used the spring or observed the flow for many years will have some weight, but must not be too implicitly relied upon. The flow should be gauged from time to time and the effect of the rainfall ascertained, bearing in mind that the flow may not be affected by even long continued heavy rains until after the lapse of some months, and that the effect of a long continued drought may not be observed until long after it has passed away. The less variable the flow, the SOURCES OF WATER SUPPLY, ETC. 287 more likely it is to be constant ; the longer the interval between a heavy rainfall or a drought and the production of any effect upon the flow, the less likely is such an effect to be serious. As a rule land springs flow most copiously in February and March, and are lowest in October and November. The gaugings therefore in the autumn and early winter are the most important, since the minimum flow is the information required. If the character of the previous summer be also taken into account reliable inferences may be drawn from the results. Small springs may be gauged by ascertaining the number of seconds required to fill a bucket of known capacity, or better still by employing a large vessel, such as a tank or tub. Or the water may be caused to flow along an open channel, or trough, when the cross section and velocity of the water in the trough can be ascertained, and an approximate estimate of the flow easily calculated. Larger springs may be gauged by damming up the water and allowing it to discharge over a board from which a rectangular notch has been cut. The notch should be two or more inches wide and the edges chamfered. The principle involved is the same as that already described for gauging streams, and the height of the horizontal surface of the water behind the dam above the lip of the notch being measured, the flow can be ascertained from the formula there given. The following table gives the discharge in gallons per minute and per day over a notch- board for each inch of width, and for varying differences of level. The quantity given in the table, multiplied by the width of the notch used, in inches, will give the yield of the spring at the time of gauging. With notches exceeding 3 inches in width the results may be relied upon ; with narrower notches they are not quite so reliable. Moreover, where the flow is so small that a notch of less than 3 inches is required, the simpler plan of actual measurement is much preferable. 288 WATER SUPPLIES Depth. Flow per Minute. Flow per Day. Depth. Flow per Minute. Flow per Day. I 31 446 2i 9-8 14,112 88 1,267 3 12'9 18,576 ^ 1-62 2,333 3i 16-3 23,472 1 2-50 3,800 4 19-9 28,656 H 3-48 5,011 H 23-8 34,272 H 4-57 6,580 5 27'8 40,032 IS 576 8,294 5i 321 46,224 2 7-0 10,080 6 36-6 52,704 It is a noteworthy fact that although springs are not abundant on the chalk formation, yet some of the largest springs in the country arise in the chalk. The following are quoted from Hughes's "Waterworks" : " Chad well, near Hertford, yielding from 2,700,000 gallons up to 4,500,000 gallons per day. "Woolmer, in the valley of the Lea, yielding 2,700,000 gallons per day. " Grays Thurrock Springs, now pumped up for the supply of Brentwood, Romford, etc., capable of yielding 7,000,000 gallons per day. "Nine Wells, near Cambridge, yielding 423,000 gallons per day. " Cherry Hinton, near Cambridge, yielding 700,000 gallons per day." Where a spring is not available attention will probably be next directed to the subsoil as a convenient source of supply, in which case a slight knowledge of the geology of the district may be invaluable. The points to which atten- tion must be directed have been referred to in the chapter treating of "subsoil water." The character of the strata within reach being known, and the directions in which they dip and the depth and position of the nearest wells having been ascertained, the presence or absence of water at any particular spot may usually be predicted, as well as the depth at which it will be reached. Where the subsoil is permeable and the water held up by an impervious stratum beneath, SOURCES OF WATER SUPPLY, ETC. 289 depressions in the ground, and spots upon which herbage is most abundant or appears greenest, will often indicate where the water most nearly approaches the surface. At sunrise and sunset films of vapour (mist) usually arise first over the damper portions of an area, and continue of greater density there than elsewhere. " On a dry sandy plain, morning mists or swarms of insects are said sometimes to mark water below" (Parkes). Near streams and near the coast water is generally found at a slight depth. This is the sub- soil water flowing towards its natural outlet. Near the sea, however, the wells may and often do yield brackish water. Even when some considerable distance from the coast, the continued maintenance of a low level in the well may result in the water becoming saline. During a recent exceptionally ^ dry season, the water in a well supplying a town on the ^ coast was markedly affected, although the well was 1 J miles 03 from the shore. The chlorine, which is normally about 3 j grains per gallon, gradually increased, until a maximum of *J 18 was reached. In hilly districts water is most likely _, to be found in the lowest portions of the valleys. Where -> the water-bearing stratum is covered with an impervious 2S one, the search for water is much more difficult, but a jx; careful study of the local geology, to ascertain the dip ^J of the various strata and the thickness of those lying ^ above the water-bearing rock, will usually lead to reliable inferences being drawn. This is not invariably the case, however. Thus in Essex a considerable portion of the 3 London clay is capped with drifts of sand and gravel and boulder clay. The sand and gravel lying between the London and the Boulder clay varies in thickness, and in some places is entirely absent, and it is often impossible to predict whether, by sinking at any particular spot, water will be found or not. This uncertainty has led to "water-finders" being employed, and as there is a pretty general belief in the powers of the hazel-twig in the district, it would appear as if the finders were usually u 29 o WA TER SUPPLIES successful. I have paid some attention to this subject lately, and find that from the manner in which the hazel- twig is held, by imperceptible muscular movements it can be made to rotate between the hands. I have seen the water-finder walk over places where water existed in abund- ance without the twig indicating its proximity. In localities which have been traversed by the finder, I have usually found that there was no difficulty in indicating where water could be obtained without the use of a hazel -twig. In one instance the hazel-twig gave strong indications of the presence of water at a point at which I was certain there could be no water within 300 feet, since the soil was of clay; and in that particular district it was known to be 300 feet in thickness. The owner of the land, however, had every confidence in the water-finder and proceeded to dig a well. When he had penetrated the clay to a depth of about 100 feet and found no indication of water, his confidence vanished, and the work was abandoned. A gentleman with whom I am acquainted contends that the hazel -twig in his hands gives reliable information. He believes that the presence of the water affects him person- ally, and the twig through him. Twigs of other trees do not answer, since they do not possess the necessary elasti- city, and cannot be made to rotate nearly so readily as the hazel. He has certainly, recently, been able to indicate the presence of water in unsuspected places, and as in his case there can be no suspicion of intentional decep- tion, the result must either be due to accident plus unconscious cerebration, or to some, at present, inexplicable influence of water upon himself or the twig. His last success is recounted in a letter which he addressed to me on 19th May 1894. He says, "General - asked me if I would give my opinion upon the practicability of finding water in a field facing his house. I went over and marked out two spots, and at each of these places digging was commenced, and at less than 10 feet from SOURCES OF WATER SUPPLY, ETC. 291 the surface water was found. ... I should add that some time since an engineer made experiments upon the same ground with boring apparatus, but gave it as his opinion that within the area no water was available." According to the geological drift map, the parish in which General resides is partly on London clay, partly on gravel, and partly on boulder clay capping the gravel, and it would seem an easy matter to indicate almost the exact limits of the area in which water could be found. In justice to my friend, however, I must add that he knew nothing of the geology of the district. Certain points requiring attention in selecting the site for a well are referred to in Chapter IV., and the possible effect of the pollution of the drainage area of the well, and the dimen- sions of this area, are discussed in Chapter XI. Before works of any magnitude are undertaken for utilising subsoil water, the area of the collecting surface should be ascertained, its con- figuration, etc., considered, and the depth of the ground water and the extent of its fluctuations determined. The less the fluctuation the more likely is the supply to be permanent, and the less the liability to contamination. Rapid fluctuations usually indicate variation in quality, as well as quantity, of the available water. Where limited amounts only are required, and the possibility of finding water or of determining the quantity available cannot be inferred, from the absence of similar wells in the vicinity, trial borings or sinkings must be made. The character of the strata penetrated must be noticed, and the boring continued until water is found or an impervious stratum reached. Into the latter it is unnecessary to bore unless it is believed to be of but slight thickness, and the water above it is not sufficiently abundant. Thin beds of clay are sometimes found in thick gravel drifts, and they hold up a certain amount of water, which is obtainable by pumping. When the clay is penetrated, the gravel beneath may not be fully charged with water, in which case that found above will run through and be lost. This is the 292 WATER SUPPLIES explanation of the mysterious disappearance of water from certain wells which have been deepened to increase the supply or the storage capacity. Instead of the supply being increased, the limited amount previously obtainable has been lost, and the work has either been abandoned or an attempt made to reach the water, if any, held in the lower pervious layer. Where no impervious stratum is penetrated, the water when reached will not begin to rise in the bore hole, or only to a very slight extent, since it is not under pressure. In deep wells, which will be considered later, as soon as the water- bearing rocks are reached, the water begins to rise, more or less rapidly, and may even overflow at the surface. In sinking shallow wells the trial bore must be continued until the depth of water is judged sufficient. By pumping the water out of the bore hole and noting the time required for it to again ascend to its former level, the abundance or other- wise of the supply may be judged, the more rapid the rise the greater the available amount of water. The yield of a well is often gauged by the length of time required for it to fill to its normal level after being pumped dry. The depth of water and the diameter of the well being also known, the yield is easily calculated. The result so obtained is always too low, since the rapidity with which the water enters varies with the square root of the head, and the head varies with the difference between the level of the subsoil water and the level of the water surface in the well. A more accurate result therefore is obtainable by starting with the water at a conveniently low level (say at half the usual depth), and ascertaining the amount which must be pumped in a given time in order to maintain it at this level. Such experiments only indicate the amount available at that particular time, but if made after a long drought, the result will probably indicate the minimum yield of the well. Where the limited space available ne- cessitates the well being sunk near drains, sewers, cesspools, or other similar possible sources of pollution, not only should every care be taken in the construction of the well, drains, SOURCES OF WATER SUPPLY, ETC. 293 sewers, etc., to avoid contamination of the water supply, but the risk should be reduced to a minimum by sinking the well in such position that the flow of the subsoil water shall be from the well towards the drains, and not from the drains towards the well. In villages and on farms the ground water is usually so polluted as not to afford a safe supply, however carefully constructed the well. In such cases, however, good water can often be obtained at a little distance away in the direction of the higher ground -water level. This distance will vary in different places according to the porosity of the subsoil, slope of the ground water, and amount of water to be pumped. Where water is only pumped in small quantities at a time, the influence of the pumping will extend but a short distance from the well ; but where a supply tank or water butt has to be filled from time to time, the level of the water in the well may be considerably depressed and the drainage area be greatly extended (vide Chap. XL). According to the permeability of the subsoil, the area capable of being drained by the well will vary in diameter from 15 to 160 times the normal depth of water in the well. In a loamy soil a distance of 20 times this depth may be sufficient for safety; in very coarse gravel the distance should be 150 times the depth. Where the slope of the ground water is steep there might be safety within these limits, as the influence of the pumping would not nearly be so marked at the side of lower water-level ; but as the plane of saturation is usually nearly horizontal it is best to err on the side of safety and regard it always as such. Whether the water should be obtained by sinking an ordinary well or by driving a tube well, may be decided after considering the advantages and disadvantages and relative cost of the different kinds of well as described in Chapter XVIII., on " Well Construction." Where springs are not available, and water is not obtain- able from the subsoil, the possibility of obtaining a supply from a deep well may be considered. As this is a some- what serious undertaking, probably attention had better be 294 WATER SUPPLIES directed in the next place to the supply which can be obtained directly from the rainfall. It is agreed that about half the rain which falls upon the roof or similar impervious surface during the whole year can be collected. The other half is lost by evaporation and by waste from the separators and filters. Why should not this rain water be stored and utilised ? Even where water is obtainable for drinking purposes from springs or wells, it may be so hard or so limited in amount that it is desirable to collect the rain water for use in the laundry and for personal ablution. A fair- sized mansion has often a roof area sufficiently large to collect enough rain water for drinking, cooking, and general domestic purposes. Assuming the area covered by the roof to be \ of an acre (1210 sq. yards), and the minimum rainfall 20 inches, then 10 inches of this may be collected. As a fall of 1 inch upon an acre represents 22,620 gallons, 10 inches upon \ of an acre represents 56,550 gallons for the year, or 155 gallons per day, a supply which would suffice for ten persons, allow- ing 15 gallons per head, or for fifteen persons at 10 gallons per head. In most parts of the country the minimum rainfall reaches 25 inches, therefore admitting of a more abundant supply. Where the roof surface is not sufficiently large it has been proposed to prepare a plot of ground for the purpose. The best method of collecting, storing, and utilising rain water was discussed when treating of rain water as a source of supply (Chap. II.), and that section must be consulted for further details. Where larger quantities of water are required, as for villages and towns, it may be derived from the rainfall on natural gathering grounds, from the subsoil, from springs, from deep wells, or from streams. Water collected in hilly districts from uncultivated surfaces, forms, as we have already seen, one of the best and purest supplies obtainable. A large number of towns in this country are supplied from such sources. Unfortunately in several instances the amount of water obtainable in the area of the watersheds has been over- SOURCES OF WATER SUPPLY, ETC. 295 estimated, the result being that in exceptionally dry seasons something like a water famine has occurred. The approxi- mate determination of the amount of water which can be collected from the surface over a given area is one of the most difficult problems in water engineering, since it depends upon so many factors, some of which (the meteorological conditions) are so variable as almost to defy our efforts to predicate their possibilities. Upon these meteorological con- ditions, so variable in themselves, depends in a very great measure two other factors the loss by evaporation and by percolation. The only factors which are uninfluenced by the weather are the area, configuration, and character of the col- lecting surface. The 6-inch ordnance maps give the contour lines or lines of equal altitude drawn at every 25 feet. The ridge or watershed lines are also marked, and from these the ground slopes downwards on both sides. These lines are continuous, save on the side which forms the natural outlet of the water collected in the enclosed area of gathering ground, technically known as a "drainage area" or "catch- ment basin." In one such catchment basin, branching ridge lines may form two or more secondary drainage areas. The area from which the water is to be collected may either be ascertained by actual measurement or be calculated from an ordnance map. The configuration, character of the surface and of the subsoil, and nature and amount of vegeta- tion, require careful examination, since they influence greatly not only the amount of rainfall which percolates, but also the amount of loss by evaporation. A portion of the water which penetrates the ground in one part of the area may re- appear in another part as springs, or it may be that the springs fed by the ground water lie entirely outside the boundary of the watershed, in which case a further portion of the rainfall escapes collection. Where the hills are steepest, the rocks hardest, barest, and most impermeable, the loss both from evaporation and percolation will be smallest. The more permeable the .296 WATER SUPPLIES subsoil, the more abundant the vegetation and the less steep the slopes, the greater will be the loss by evaporation and absorption. Where the soil is peaty, where moss abounds and bogs are extensive, much water is retained ; it neither runs off the surface nor percolates into the subsoil, but is slowly lost again by evaporation. The loss by percolation is greatest where the subsoil is very porous as when it con- sists of sand and gravel and when the outlet for the ground water is outside the collecting area. However, as a rule, the localities selected as gathering grounds for water supplies have but a small proportion of their areas covered with any depth of permeable subsoil, since such ground is objectionable, not only because of the amount of water which it permits to percolate, but because, in this country at least, it would be cultivated or used for pasturing cattle, and would there- fore tend to pollute the water. The amount of water which may be lost by percolation has been referred to in Chapter IV. Both this and the loss by evaporation are affected greatly by the character of the rainfall. If the rain descends in frequent slight showers, the whole may be lost ; whereas if the same amount falls in a few heavy downpours, a large proportion will run off the surface and may be collected. In the hilly districts selected as gathering grounds the rain- fall is not only usually more abundant than in the plains, but it descends in sharper, heavier showers. As the water collected from any given area would otherwise have found its way into some stream or formed the natural source of such stream, the problem of ascertaining the amount of water which can be collected is frequently the same as that of determining the amount of water available from such stream. These we have already considered in Chapter VII., under the heads of (a) area of watershed, (b) the topography and geological character of the ground, (c) the average rainfall and the rainfall during a consecutive series of dry years, (d) the seasonal distribution of the rainfall, (e) the amount of water which must be supplied for "compensation" SOURCES OF WATER SUPPLY, ETC. 297 purposes, and (/) the facilities for obtaining storage. Based upon this knowledge engineers have devised formulae for estimating the probable daily yield of a catchment area. Dr. Pole's formula is Q = 62A(f Rw-E). In this equation Rm represents the average rainfall of a long series of years, and i Rm the estimated average of the three driest consecutive years. E = the loss of rainfall by evapora- tion, percolation, and unavoidable waste; and A = the area of the gathering ground in acres. As 1 inch of rainfall upon 1 acre represents 22,620 gallons of water, the average amount of water which can be collected yearly during the three driest consecutive years would be 22620Ax(iRw-E). Since 22,620 divided by 365 is approximately 62, Pole's formula gives the mean daily yield of water from the catchment area. The importance of the factor E is evident, and it is to the fact that this has been occasionally under- estimated that the scarcity of water in certain towns during long-continued periods of low rainfall is chiefly attributable. In some cases, however, the fault has been due to the reservoirs not having been sufficiently capacious to allow of the accumulation of an ample reserve to tide over such periods of drought. Under any circumstances the most capacious reservoirs may become filled, and rain continue to descend and pass down the bye-wash and be wasted. This unavoidable loss Mr. Hawksley estimates at one-sixth .of the rainfall. The loss by evaporation and percolation which, as we have seen, depends upon so many factors is variously estimated by engineers who have studied this subject. Mr. Hawksley found at Sheffield that it was nearly 15 inches, "although the ground is very elevated, ascending to 1500 or 1600 feet; but it lies rather with a southern aspect, and the ground is mossy, and a good deal of water is held superficially, and of course is re-evaporated." In this 298 WATER SUPPLIES country the loss by evaporation and percolation is given by the following authorities as under : Mr. T. Hawksley, 11 to 18 ins. Average 14 ins. Dr. Pole, 12 to 18 ins. Mr. Humber, 9 to 19 ins. Average 13 to 14 ins. Mr. Bateman, 9 to 16 ins. Over most favourable areas, therefore, the loss may not exceed 9 inches, whereas over the most unfavourable ones which are likely to be selected as gathering grounds it may be as high as 19 inches. The value of E in Dr. Pole's formula, therefore, will vary from (unavoidable waste) 4- 9 to Rw , T q ~6~ H In an excellent report recently issued by Dr Porter, the Medical Officer of Health for Stockport, on the water supply to that borough, there is an admirable illustration of the use of this formula. The Disley gathering ground from which the town is supplied has an area of 1700 acres. The average rainfall thereon during the last twenty-six years has been 48-6 inches. The loss by evaporation and percolation he takes as 14 inches, and the loss by unavoidable waste one-sixth the average rainfall, or 8 inches. E therefore = 14 + 8 = 22, and the equation becomes Q = 62 x 1700 ( of 48-6 - 22) = 1,779,152 gallons. As the average daily consumption of water is 1,750,000 gallons, the assumption is that even with reservoirs of suffi- cient magnitude the available water is only just enough to meet the present requirements of the borough. The amount of storage necessary to render the required amount of water available during the longest drought varies considerably in different places. Where the rainfall is heaviest the storage necessary is least, and vice versd. Over the western half of this county, and in the more mountainous districts, 120 days' storage has been found sufficient, but in SOURCES OF WATER SUPPLY, ETC. 299 the eastern counties a storage for 300 days might even be required. In such districts, however, surface water is very rarely used for town supplies. There are few suitable col- lecting areas, and the rainfall is too low and too varied in its seasonal distribution to justify any attempt to obtain water from such sources. In those parts of England in which sur- face water can be rendered available a drought extending over 120 days, or a succession of droughts corresponding to that period, must be so rare as to be phenomenal. In works of such vast importance all errors must be on the safe side ; it is wisest, therefore, to make provision for 150 days' drought even in districts with heavy rainfalls, and in less favoured districts to provide for the storage of 200 days' supply. This appears to be the general opinion of the most eminent engineers. It is impossible to give any precise rules as to the relation of the rainfall to the amount of storage. Mr. Hawksley's well-known formula gives results which confirm the opinion expressed by Dr. Pole, quoted below. Let D = the number of days' storage necessary, and F = the mean annual rainfall of a long series of years, then according to Hawksley With a rainfall of 25 inches this formula gives 200 as the number of days' storage required ; with 49 inches 143 days would suffice. Dr. Pole says " the general judgment of ex- perienced practitioners appears to be that for large rainfalls a storage of 150 days or even less will suffice, but in drier districts it may be necessary to go as high as 200 days ; . . . and this is a provision which may reasonably be borne." The extent to which the character of rain water can be affected by the surfaces from which it is collected was referred to in Chapter III. Subsoil water is not utilised nearly to the same extent for supplying towns as surface and river water, whilst rural communities still continue to be supplied chiefly from this source. The factors upon which the amount of water avail- 300 WATER SUPPLIES able in the subsoil can be estimated have already been con- sidered (Chap. IV.). A single well may yield sufficient water for a large village, or if the subsoil be chalk or sandstone and admit of headings being driven in various directions from the bottom of the well, one well may even supply a town of moderate size. Usually, however, two or more wells are required, necessitating a corresponding number of pumping stations and a considerably increased expenditure. A village may sometimes be supplied from a single well in a patch of gravel, but usually such drifts are not sufficiently extensive or thick to yield a constant supply of any magnitude. A parish in one of my districts is supplied from a well sunk in the sand. The well is only about 1 2 feet deep and is capable of yielding 22,000 gallons of water daily in very dry seasons. Upon the same gravel patch and within 100 yards of the well is the parish churchyard, but beyond this, springs out- crop, and the water level in the well is 1\ inches higher than in the trial bores made near the graveyard. The infer- ence, therefore, is that the direction of flow is from the well towards the church. The effect of forced pumping was tried, and as this did not in any way affect the quality of the water it confirmed the above conclusion. Assuming also that the water in the well was kept constantly at 8 feet below its normal level, and that the drainage area of the well is thirty times the depression, the churchyard would still lie beyond. But as the character of the drift renders it probable that the drainage area will be little more than twenty times the depression, and as this low level is rarely reached and never maintained for more than a few hours, the margin of safety is ample. (The underground accumulating reservoir or well holds 14,000 gallons. It is built of 9-inch brickwork in cement, 16 feet deep, with strengthening piers, and covered with 6-inch cement concrete laid on rolled iron joists. The tower is of red-brick, 24 feet to bottom of tank. The tank is of wrought iron, circular, 15 feet in diameter, and 12 feet deep, and is encased in brickwork, the total height of the tower SOURCES OF WATER SUPPLY, ETC. 301 being 42 feet. The lower portion of the tower is used as the engine-room, in which is a 2J h.p. engine with vertical boiler, capable of raising about 4000 gallons of water per hour. The mains are ordinary cast iron of 4 and 3-inch diameter, turned and bored and coated with Angus Smith's composition. The well is about 1 mile from the centre of the village. The total cost, exclusive of land, was ,1350.) The chalk formation in most cases contains a large store of excellent water, but a single well, even with headings, rarely yields enough water for a large town. The drainage area of chalk wells cannot be estimated, since the water exists chiefly in and travels through the fissures, and but very slightly, if at all, through the chalk itself. It is evident therefore that the freedom with which water percolates through a chalk subsoil will depend upon the abundance and size of these fissures. If the fissures are numerous and large the drainage area may be very considerable. The well referred to on page 289 as being affected by the sea, IJ miles away, is sunk in the chalk. Cases are also recorded in which impurities have been found to enter a well after travelling a very considerable distance through such fissures. As an example of the amount of water obtainable from wells in the chalk, the case of Croydon may be cited. The old waterworks are close to the town, and comprise four wells sunk in the chalk within a space of 100 feet square. The level of the water in the wells is not more than 25 feet from the surface, and the fissures yielding the chief portion of the supply are about 25 feet lower. Over 3,000,000 gallons per day have been pumped from them. To meet the increasing demands of the town a new well was opened in 1888. This is sunk 200 feet, all in the chalk, and is 10 feet in diameter. Water was first found at 87 feet. At 142 feet from the surface and below headings have been driven. The yield from the well was 130,000 gallons a day, but the first fissure cut by a heading increased the daily yield to 600,000 gallons, and when the yield reached 2,500,000 gallons a day the work in the well had to cease 302 WATER SUPPLIES through the inability of the two 24-inch pumps to keep the water down. The total length of the headings is 813 yards, and they are generally 6 feet high and 4^ feet wide. The storage capacity of these and the lower part of the well is about half a million gallons (Borough Engineers Report, 1890). A well such as that just described is usually spoken of as a " deep " well, although sunk entirely in one pervious stratum. The chalk, new red sandstone, oolite, and green- sand contain vast stores of water of excellent quality access- ible over very large areas to the well-sinker or borer, but it must not be forgotten that there is a little uncertainty in searching for water at such depths. The most experienced geologists are sometimes at fault. The variations in thickness of the water-bearing stratum and of the strata resting upon it, the possibility of hitherto unsuspected faults existing, must all be borne in mind. The water, also, when found, may be quite unsuitable for domestic purposes. Thus in Essex many of the borings piercing the London clay yield a water containing so much sulphate of magnesia as to be aperient in property, whilst others have yielded a water so brackish as to be useless. The presence of beds of gypsum and of rock salt in the new red sandstone must not be forgotten, the former rendering the water excessively hard and the latter salty. At Rugby a well sunk 1200 feet yielded only brackish water, and at Middles- borough a well which was sunk for obtaining a pure water yielded so strong a brine that salt is extracted from it. At Wickham Bishops, Essex, a boring was sunk to a depth of about 1000 feet without water being found, yet everything had indicated that an abundance of water would be reached at a depth of about 500 feet. The section showed that there existed a previously unknown and unsuspected fault crump- ling the London clay back upon itself, so that this stratum had to be twice pierced. When the second layer had been penetrated and no water discovered the work was abandoned. In other places the fall in the water-level from the heavy continued pumping indicates that a time may come when SOURCES OF WATER SUPPLY, ETC. 303 such supplies will fail, and unless the site of the well has been carefully chosen, others may be sunk in such positions as seriously to affect the supply. The amount of water obtainable from a deep well in any particular locality is difficult to predict, but a consideration of the conditions bearing thereupon, referred to in Chapter VI., will assist us in arriving at fairly safe conclusions. The information contained in the next chapter, gathered from experienced well -sinkers, engineers, geologists, and others, showing the actual amounts of water which have been obtained from various underground sources during recent years, will also be a useful guide. It is advisable in all cases to derive the whole supply required from one and the same source. In many towns, especially on the Continent, water is derived from a number of different sources. This may have been due to the original supply proving inadequate on account of the increase in population and the increased consumption of water required by a higher standard of cleanliness. In Paris a dual system of supply has been adopted. The one furnishes unfiltered river water, and is used for municipal purposes and for supplying baths, fountains, etc. The other furnishes a purer water, derived chiefly from springs in the valley of the Vannes. The suggestion to adopt such a dual system else- where has not been favourably received. Apart from the enormous additional expense necessitated by a duplicate system of mains, it has many other objectionable features. At Berlin the water of the Spree, after filtration, supplies a portion of the inhabitants, whilst others are supplied from the Tegeler Lake. Vienna derives water from springs in the Styrian Alps and from wells sunk in the subsoil on the banks of the Schwarza. The water supply to Brussels is most un- satisfactory, and is derived from the subsoil, from the Harre, and from the drainage of the Forests of Soignes and Cambre. The Leipzic water-works present several peculiarities. Water from the Pleisse is run into reservoirs, and the water filters 304 WATER SUPPLIES through the natural gravel bottom, and is collected in earthen- ware pipes, with open joints, which are laid in the subsoil for this purpose. This supply is supplemented by the yield from five groups of Artesian wells. The water supplying Stockholm is derived in part from a lake and in part from the subsoil, almost exclusively from the latter during the winter months. Interesting details of these arid other works are given by Palmberg and Newsholme in their Treatise on Public Health and its Applications in different European Countries. CHAPTEE XVIII WELLS, AND THEIR CONSTRUCTION THE practice of obtaining water by means of wells sunk in the subsoil is one which dates from the remotest antiquity, and at the present time a very large proportion of the popula- tion of the globe derives its supply of water from such sources. In Great Britain it is estimated that over one-third of the population is so supplied. Whilst in every other depart- ment of engineering improvements have advanced with rapid strides, especially in recent years, shallow wells continue to be constructed in almost precisely the same way as they were thousands of years ago. The well-sinker is the most conserva- tive of men, and in most districts it is impossible to get a well constructed so as to protect the water from pollution. To the country well-sinker a well is merely a reservoir to contain water, and whether this water enters from the bottom, side, or top he considers a point unworthy of consideration, and in fact he makes the well in such a manner that water can freely enter it at all points. The result is, that as wells are, for convenience, almost invariably sunk in close proximity to inhabited houses, impurities from the soil, from defective drains, cesspits, and cesspools readily gain access and foul the purer water which enters at a greater depth. It is not surprising therefore that the great majority of such wells yield water which is always impure, and liable at any moment to become specifically contaminated and produce an outbreak of disease. The time-honoured custom of lining the well x 306 WATER SUPPLIES with bricks, set dry, and resting upon a wooden curb, still almost universally prevails. The brickwork may be carried right up to the surface and the well left open, or it may be covered with a lid, in which case it is frequently so left that the water spilt upon withdrawing the bucket runs back into the well, carrying with it filth from the surface of the ground around, and during a heavy rainfall the surface water runs directly into the well. Where the well is covered up, the cover is generally near the surface, and may consist of old railway sleepers or logs of wood admitting water freely. Even if no sewage matters enter such wells, the wooden curb and the rotting wooden covering yield putrid organic matter to the water. Draw wells and dipping wells are also liable to be contaminated by the dirty vessels let down into them, by frogs, rats, and other animals getting in, and by dead leaves and other matters blown by the wind. The animal and the vegetable substances by their death and decay foul the water. In wells otherwise carefully constructed it is often found that impure water can gain access along the track of the pipe leading from the pump to the well. In a properly-constructed well no water should be able to enter except from near the bottom, so that before reaching the well it must have passed through a considerable thickness of subsoil, becoming in its course thoroughly filtered and purified. Various methods of accomplishing this difficult task have been suggested; but as there are other ways of obtaining subsoil water, which are more simple and far more satisfactory, we may reasonably hope that ere long the ordinary form of shallow well will be abandoned. Before describing these other methods, however, the best ways of constructing wells may be briefly referred to. Where the excavation is through solid rock, such as chalk, limestone, or sandstone, the steining, or lining with a cylinder of brickwork or of iron or other material will only be necessary to keep out the water from the more pervious surface soil. If bricks be employed they must be well bedded on the rock with WELLS, AND THEIR CONSTRUCTION 307 cement, and the whole of the brickwork lined inside with hydraulic cement, and the lining continued some distance below the last layer of bricks on to the exposed surface of the rock, so as to render the junction as impervious as possible. The brickwork should also be well puddled behind. Where the rock is not freely porous water may accumulate in the loose subsoil, and unless the greatest care be taken it will enter the well. In the most modern wells cast-iron or wrought-iron cylinders are employed for lining the upper portion in order to keep out the surface water and land springs. Similar cylinders are also employed to keep out water from fissures which may be met with in excavating the well. Where the subsoil is clay and impervious these pre- cautions are of course not necessary. In ordinary wells, sunk throughout in a porous subsoil, the lining should consist of two separate rings of 4J-inch brickwork laid in cement and lined with cement to a depth of 10 or 12 feet from the surface. As this class of work is somewhat expensive, and the cement is liable to fracture, either by the inward pressure of the sides of the well or other causes, earthenware tubes are now being made by the Leeds Fireclay Company for lining purposes. .These tubes have an internal diameter of 2 feet 6 inches, and cost 17s. 6d. each. The upper edge is bevelled internally and the lower externally, so that the lower edge of the upper tube fits like a wedge into the upper edge of the tube below it, and there are no projecting surfaces outside to retard the downward movements of the tubes. The ground having been excavated as deep as can be done with safety, a tube is dropped in and some well-puddled clay laid on the bevelled edge and another tube lowered. If properly driven the tubes fit well together. The tubes are lowered by aid of ropes, blocks, and cross-bars. Having got in the tubes, a collier can easily work inside and undermine the edge, when the weight will cause them to descend. Clay is preferred for the joints, because cement breaks when the tubes are being lowered. Of course the joints can afterwards be "pointed" 308 WATER SUPPLIES inside with cement so as to make them more secure, and it is advisable to try all the tubes, fitting and marking them before using. Mr. Tudor, who has introduced these tubes, informs me that he has put down in this way as many as twelve 3-feet tubes in silty land. Other well-sinkers use a wooden curb or crib of 3J feet in diameter. This is suspended and lowered in the usual manner, and supports the tubes placed upon it. The space between the ground and the tubes is filled in with well-puddled clay. Or the well may be constructed in the ordinary manner, dry steined with 4j-inch brickwork if necessary, and the tubes then lowered and fitted and puddled behind with clay. Dry-steined wells at present in existence might with advantage be converted into tube wells in this manner. The well itself having been so constructed as to prevent the possibility of water entering anywhere except at the bottom, it remains still to cover it in and protect the top. The best plan is to project the dome of the well 6 or 1 2 inches above the surface of the ground and securely cover with a properly-fitting iron cover. By this means easy access is at any time gained for cleansing or examining purposes. The pump should be fixed some little distance from the well, and the drain carrying away the waste water should not go near it. Every care should be taken to render water-tight the aperture through which the pump pipe passes, and it should be bedded in clay or cement so as to prevent the water or rats forming a track alongside the pipe through which impurities can gain access to the water in the well. If the sides of the well be covered up to a sufficient height above the ground, the pump may be fixed inside, the handle and spout only projecting outside. A hooded aperture at the top can be left for ventilation. Quite recently I have seen wells the upper portions of which were constructed from the halves of old steam boilers, the domed end of the boiler forming the top of the well and a hole being drilled through the side for the pump pipe to enter. To prevent the action of a soft water upon the iron, WELLS, AND THEIR CONSTRUCTION 309 it is desirable that the whole of the interior should be lined with cement. Koch, in his work on Water Filtration and Cholera, whilst condemning strongly the ordinary shallow well, recognises the fact that it is impossible to arrange that those already existing should be abandoned. He therefore recommends that the construction should be so altered as to remove all danger of contamination from above. " To achieve this, one should proceed by filling up the well to the highest water point with gravel, and over the gravel with sand up to the very top." Of course an iron pipe should traverse the sand and gravel and be connected with the pump. A well so constructed "gives the same protection against the infection of water as is given by the sand filtration of the great waterworks. In fact it really gives a greater protection, since it is not exposed to the many disturbances in the process of filtration already referred to, and is also not affected by frost." So much attention is now being given to perfecting as much as possible the water supply of the great waterworks, that it is important not to lose sight of the domestic water supply by pumps and wells. By improving the wells in the manner explained above, "the spread of cholera, 1 in so far as it is due to water, can be restricted to a great extent. It is just in this respect that a great deal can yet be done." This suggestion of Koch's is one worthy of all consideration, since the change can be effected at a minimum of expense, and the result leaves little to be desired. It is important, however, to remember that the superficial layer of sand should be at least 6 feet in thick- ness. Where the subsoil water is reached at a less depth than 6 feet, probably this method will not afford complete protection in many cases. Dr. R. Kempster, in his researches on "The influence of different kinds of soil on the cholera and typhoid organisms," arrived at the following conclusions : " White crystal sand, yellow sand, and garden earth have no 1 And of typhoid fever and other diseases disseminated by water. 310 WATER SUPPLIES marked favourable or injurious action on the life of the organisms. The length of life of the organisms in the soil depends chiefly on the amount of moisture present. Peat, on the contrary, is very deadly to both the comma and typhoid bacillus. The soil acts as a good filter, holding back most of the organisms, but it is possible for these organisms to be carried through 2 J feet of porous soil by a current of water." Where the ground water-level, therefore, is within 5 or less feet from the surface, the side of the well should be rendered impervious to a depth of 10 or 12 feet, or, better still, the water should be obtained by aid of an Abyssinian tube well, next to be described, driven to at least this depth. In a great many instances subsoil water can be obtained without the trouble and expense of well-digging, merely by driving iron tubes through the ground until the subsoil water is reached, and fixing a pump to the upper end of the tube. Such tube wells were first used systematically during the Abyssinian campaign, hence they are now popularly known as "Abyssinian" tube wells. They are most suitable for gravel, coarse sand, chalk, and similar porous water-bearing strata, and for depths not exceeding 40 to 50 feet, though under exceptional circumstances tubes have been driven successfully to a depth of 150 feet. Naturally they cannot be driven through hard rock, neither are they suitable for obtaining water from marl, fine sand, or clay formations, sirce the apertures in the perforated terminal tube are liable to become blocked by the fine particles of which such strata are composed. A pointed perforated tube is driven into the ground by aid of a "monkey." (The tubes vary from 1-J to 4 inches in diameter, according to the amount of water which it is desired to raise.) When this tube has been well driven, a second tube is screwed on to the first and the driving resumed. By lowering a plummet down the tubes from time to time, it can be ascertained whether water has been reached or whether sand or earth is filling up the end of the perforated tube. When water is reached a pump can be attached and WELLS, AND THEIR CONSTRUCTION a sample drawn for examination, and the quantity available ascertained. If either the quantity or quality be unsatisfactory, the tubes can be driven deeper or they can be with- drawn and redriven in another spot. A well of this character is shown in Fig. 20. Very often, where the supply from an ordinary sunk well is limited, it can be increased by driving one or more of the "Abys- sinian " tubes from the bottom of the well. Special pointed and perforated tubes are employed where the soil is ferruginous or likely to corrode the metal of the ordinary tube. Tubes designed to prevent plugging with sand are useful under certain circum- stances, as when the water-bearing strata contains together with the sand a fair proportion of grit. In fine sandy soils, however, it is better to withdraw the tubes, ram down a lot of fine gravel, and redrive. In the " Abyssinian " tube well the water is drawn directly from the water-bearing stratum, there being no reservoir. At first the water invariably contains fine sand or chalk, according to the nature of the subsoil, but after a time a clear water is yielded. This is probably due to the removal of all the fine particles and debris from around the terminal tube and the formation of a natural cavity in which the water accumu- Fio. 20. Abyssinian Tube Well. 312 WATER SUPPLIES lates. In suitable localities these tube wells answer admirably, and not only are cheaper to sink, but yield a safer supply of water than a sunk well. One man, usually, can drive the smallest -sized tubes, but three or four men are required for the largest tubes. In very light soil a 30-feet well may be driven in less than one day ; in a firmer soil three days may be required. Whatever the depth of the tube well an ordinary pump will raise the water, provided the water level in the tube is within 25 feet of the surface. If the water stand at a lower level, a deep well pump must be pro- vided. The capacity of these tube wells varies with the depth, yield of spring, and power of pump applied. The following are the estimates of two of the best-known firms of well-sinkers. Size of Well. Yield in Gallons per Hour. Authority. 1| in. 150 to 600 Le Grand and Sutcliff 2 300 to 1200 J5 ) J 3 600 to 2400 4 1200 to 4400 - 5 > 5 1* - 150 to 900 C. Isler and Co. 2 300 to 1500 3 450 to 3000 33 J3 Messrs. Le Grand and Sutcliff have kindly furnished me with the following table (see page 313), giving the depth of well, size of tube, yield of water per hour of a series of typical wells driven by them, which bear out the above statements. Not only are these tube wells preferable to sunk wells on account of the greater freedom from risk of contamination, but they are much less expensive. The probable cost of a well can easily be calculated from the following estimates (see page 314). WELLS, AND THEIR CONSTRUCTION 313 rf P ooooooooooooooooooooooooooooco ' p CO | p g o J g c3 i o o o o o o o o o o o o o o o PH 1 1 fc fefcfefefefefefefeW.fe W o c3 fe p ^^ ^ a 1 s^sssssssssssfes ^ s 1 ^ ^^to^o ^- O o to ID EH 1 -SSSS"* SS M s 1 1- 1 02 g f g = ^ ^O 'o T3 'QJ r^J r^-J ^ ^ 'S ^rQ r ce r d 5 -fl^fl^^'ls^ ~ r e8 s <1 1 ^S S ^SfH 0803 ^^^ "ra* " 1 T; > 1 ^cS 1 1 >, ,Q a Jt r I 314 WATER SUPPLIES Twelve-Feet Tube with Hire of Plant and Man to Superin- tend Driving. Add for each additional Foot. Pump, Column, and Foundation. IJ-inch tube 2 ,, 3 4 240 3 10 7 10 9 15 3s. 4s. 6d. 10s. 13s. 2 10 to 3 10 3 10 to 4"lO 5 J > 5 To the above must be added the man's time in travelling, railway fares, carriage of materials, etc. A well driven recently in one of my districts to a depth of 17 feet, a 2-inch tube being used, cost 8:12 : 4, the items being as under. 17-feet 2-inch tube well . . . . 2 14 6 4-inch column, pump, and foundation . 380 Hire of man and plant . . . . 1 10 Man's time travelling . . . . 076 Railway fare and carriage . . . 0124 Total 8 12 4 The wages of the agricultural labourer who assisted in driving the tube is not included, but would not exceed 5s. These prices may be compared with the following schedule of prices taken from Sir E. Rawlinson's Suggestions as to the Preparations of Plans for Drainage and Water Supply (Local Government Board, 1878). Schedule of prices for sinking wells in Clay, lined with 9-inch brickwork in Portland Cement, Wooden curves, cylinders, and pumping extra. 4 feet diameter to depth of 200 feet, 50s. per foot run. 5 200 65s. 6 200 85s. 7 200 105s. Rough estimate of well-sinking, through Clay, Chalk, and Gravel, entirely exclusive of brickwork or fittings. Diameter of Well. Depth. Price per Foot of Depth. Total Cost. 4 feet 5 ,, 50 feet 50 ,, 3s. 4s. 6d. 7 10 11 5 WELLS, AND THEIR CONSTRUCTION 315 Where hard rock has to be pierced or where the water- bearing stratum lies at a considerable depth below the ground surface, the well must either be excavated or bored. The cost of sinking as compared with boring is so excessive that nearly all deep wells are now bored. Not only is the cost much less, but as the bore -hole is lined with metal tubes (which should be of wrought iron, lap -welded and steel- socketed), surface springs are excluded, and the possibility of contamination reduced to a minimum. Various methods are employed and many different kinds of tools, according to the nature of the strata to be penetrated, and the depth and the manner of the borings, which vary from 3 to 12 inches in diameter ; but in soft rock, like chalk, this diameter may be greatly exceeded. In the majority of cases the borings are made from the bottom of a dug well, the object usually being twofold : (a) to form a storage reservoir for the water ; and (b) to provide a receptacle for the pumps. It is, how- ever, found that in many cases the dug well can, with advant- age, be dispensed with. It is only really necessary where the spring is weak and the demand for water intermittent. Such dug wells, unless very carefully constructed, also increase greatly the liability to contamination by surface water. During the process of boring a number of springs may be tapped, and the quality of the water yielded by each can be ascertained by analysis. If it be ultimately found that one of the upper springs yields the most suitable water, the tubes can be withdrawn and the hole plugged at such a depth that only water from that particular spring is supplied. In the older wells the tubes lining the bore are usually not con- tinuous, and water from divers sources has free access to the wells. In the more modern borings larger tubes are used for convenience in boring, and a smaller tube with tight joints is then inserted, reaching from the surface to the bottom of the well. The outer tubes may be afterwards withdrawn or the space between the two filled in with cement. With such a continuous tube the pump can be so attached that 316 WATER SUPPLIES the water is drawn directly from the bottom of the well. The conditions which influence the yield of water from bored wells are so lucidly expressed by Mr. K. Sutcliff, in a paper read before the Brewers' Congress in 1886, that no apology is required for reproducing them here. " The continuous tube," says Mr. Sutcliff, " has an important bearing on the yield from the spring; the weight of the atmosphere being removed by the pump from the surface of the water in the tube well. This, as regards the velocity of the flow of the spring, is equivalent to drawing the water from some 34 or 35 feet lower than is possible when the weight of atmosphere presses on the surface of the water. The increase in supply under these conditions is equal to about 40 per cent, which acts as an important compensation for absence of storage. It may be interesting to give an example of this. A dug well, 25 feet deep and of 5 feet diameter, will hold 3050 gallons of water. Suppose that such a well is supplied by a spring which, when the head of 25 feet is removed from it, will flow at the rate of 950 gallons per hour. As the maximum flow is only obtainable after the storage is completely exhausted, the average yield must be taken until that exhaustion occurs. Let the pumps be started to draw 1500 gallons per hour, the quantity obtained by storage will be exhausted in two hours. But as in that time the spring would have been yielding an average flow of, say, 700 gallons per hour, the well would not be emptied until the pumps had been going about four hours. When that time had expired, the spring would be yielding its maximum of 950 gallons per hour, and the speed of the pumps would have to be slackened proportionately. Under these conditions, a total of 11,500 gallons would be drawn from the well in ten hours. " Let a tube well be placed under exactly similar circum- stances as regards supply and water level. The pumps draw- ing from a tube well could get 950 gallons per hour plus 40 per cent; that is to say, 1330 gallons per hour. Therefore, the tube well would in ten hours yield 13,300 gallons a gain, WELLS, AND THEIR CONSTRUCTION 317 in that time, in spite of absence of storage, of 1800 gallons ; and the pumping from the tube well could be continued uni- formly at the same speed for an indefinite period, so long as the spring maintained its flow. " When the normal level of the spring is not sufficiently near the surface, or the flow is not rapid enough to enable an ordinary lift pump to draw the water, the tube well must be made of such size as will enable a deep well pump to be placed in it, as far below the surface of the water as may be necessary to obtain the required supply. A deep well pump can be placed 150 or even 200 feet below the surface ; but when it becomes necessary to place it at that depth below the water level, the supply required is one that is very great compared with the spring that yields it. Because, although all springs increase until the base of them is reached, that augmentation is a constantly decreasing one. The reason for this decrease is obvious. The water flows through channels of fixed area. When the head of water is removed, the pressure is increased proportionately with the depth that the water is lowered ; but the friction of passing through the channels also increases. So that to double the supply that flows at 150 feet below the head of the spring, it would be necessary to place the pump 600 feet under the water. These facts are of the highest importance in deciding whether a given spring can meet the requirement of the consumer. Let it be supposed that two borings are made, and that springs are tapped by these borings, which both overflow the surface of the ground at the rate of 10 gallons per minute. To the casual observer both of these springs might be con- sidered as equal. But one might be ten times stronger than the other. Let us call these springs A and B. The spring A, when we lower it by pumping, gives no appreciable increase ; whereas the spring B, when we lower it only 3 feet, yields double the quantity of water. Why is this? If it were possible to carry the pipes up from which spring A flows, we should find that it would reach 100 feet before it came 318 WATER SUPPLIES to rest ; whereas with spring B, if we only piped it 1 foot higher, it would cease to flow. This would prove that spring A is a high-pressure one, the source of which is 99 feet above the ground level ; but spring B has its source only about 1 foot above the ground level. The channels of communication in spring A are small, and the friction is depriving us of the advantage of the great head of water. The channels of com- munication from spring B are free and large. One may, however, be deceived unless the test of pumping is a pro- longed one. What is known as a ' pocket of water' may appear from temporary pumping to be a spring of the B class ; but sustained pumping will demonstrate the impostor, as the water level will not recover itself without a more or less pro- longed period of rest. This proves that while the channels of communication are large, the area which is being drawn from is small. Under such circumstances a multiplication of wells would be of no advantage ; but in many instances the friction of drawing water through the earth may be largely diminished by sinking a number of tubes and coupling them together, so that one pump draws from them. What is known as the 'cone of depression' is reduced by this method of drawing the water. Tubes placed, say, 20 feet apart, may each only yield a small supply ; but the aggregate obtained from a number of these tubes becomes very large. "At the Burton Breweries, some forty or fifty 3-inch 'Abyssinian' tube wells yield 2,000,000 gallons daily; yet no one of the 3-inch tubes delivers more than 2000 gallons per hour. The area from which they draw is so extended that at no one point is the water level materially depressed. "At the Town Waterworks of Watford, a dug well of 10 feet diameter, supplied by a 12-inch boring at the bottom of it, proved inadequate when drawn from night and day to meet the requirements of the town. A single tube well of 8J inches in diameter, placed some 30 feet from the dug well, doubled the supply of water obtainable, and thus enabled the hours of pumping to be materially reduced. WELLS, AND THEIR CONSTRUCTION 319 Somewhat similar experiences were obtained at the Town Waterworks of Aldershot, Hertford, St. Albans, and Abbots Langley, all of which towns now derive their water supply from tube wells." The -imperfect construction of many of our older wells to some extent brought boring into disrepute. Thin sheet-iron was in many districts used for lining the bore. The imper- fect joints very frequently admitted the entrance of subsoil water, hence the water yielded was often polluted. In a comparatively few years the sides of the tubes corroded and collapsed, and the supply gradually, or, in some cases, suddenly failed. By the use of proper casing, such as the " Russian Brand" swelled and collar-joint casing, employed now so extensively, all these defects are obviated. The difficulty, however, of making these tubes absolutely water-tight is greater than at first would be anticipated, arid where the slightest defect exists the continued raising of water by pumps fixed directly upon the bore tube is very likely to accentuate it by the continued lateral insuction of air and water. A most instructive example of such a defect is contained in Dr. Geo. Turner's Report on the Water Supply to the Suffolk County Lunatic Asylum, previously referred to. Some years ago the prevalence of dysentery in this Asylum was attributed to the impure water supply, and a fresh supply was obtained from two bored wells, so con- structed that contamination of the water appeared quite impossible. Dr. Turner says, "The construction of these bores is very similar in principle, but varies slightly in detail. In both instances an 8-inch steel pipe with screw joints was sunk into the chalk, the bore was then enlarged, filled with cement, and the 8-inch tube sunk into the cement, which was then allowed to set. After the cement had set, a 6-inch steel tube, also with screw joints, was passed through the cement to a distance of 200 feet, when the bore was again enlarged ; the cavity was filled with cement, which was allowed to set, and then the boring was continued another 100 feet. The 320 WATER SUPPLIES total depth of the bores was 305 and 350 feet respectively. The space between the 8-inch and 6-inch tubes was filled with cement through a composition pipe passed to the bottom, and the bore was fastened to the pump by an air-tight joint." Notwithstanding these elaborate precautions, dysentery again broke out in the Asylum, and was again traced to the water supply. Dr. Turner found that after continued pumping there was a marked difference in the quality of the water drawn from the two wells, and upon excavating around the tubes and pouring into the excavation a solution of chloride of lithium, he afterwards found distinct traces of this salt in the water drawn from the pumps. From the result of these and other experiments he concluded that there was no reason- able doubt that neither of the tubes were water-tight. The danger of lateral insuction must be greater in wells in which the pump is screwed directly on to the lining tube, than in those in which the pump pipe or barrel is merely inserted within the lining tube, since the removal of the atmospheric pressure, in the former case, causes water or air to enter the bore through the most minute apertures, and in course of time such apertures enlarge, admitting impurities more and more freely. This danger, in some degree, counterbalances the advantages of the increased supply, and it would appear to be safer not to directly connect the pump with the bore tube where water can be obtained in sufficient quantity without such attachment. The cost of constructing bored wells varies with the nature of the strata which have to be pierced. Fifty years ago, local well-sinkers in Essex would pierce 300 feet of London clay, line the well, and fix a pump for a total cost of less than 100. A't the present time similar wells cost about three times that amount, and the local well-sinker has disappeared. The only explanation appears to be that it has been found more economical to employ professional well-borers, and pay treble the price for a properly-constructed well, than to employ the local men. Sir K. Rawlinson, in his Official Report to the WELLS, AND THEIR CONSTRUCTION 321 Local Government Board on Water Supplies, etc., gives the following schedule of prices for making bore-holes in red sandstone. The prices for boring in chalk and in sand and clay average Is. per foot less, but in sand and clay, where the boring exceeds 200 feet in depth, the price is, on the contrary, about 3s. per foot more than for boring in chalk or sandstone. Per Foot Run Cost of Cast or Wrought-iron Diameter. First Second Third Fourth Pipes per Foot. Inches. 100 Feet. 100 Feet. 100 Feet. 100 Feet. 3or4 5s. 6d. 7s. 6d. 11s. 6d. 14s. 6d. 4s. to 5s. 6d. 5 7s. 6d. 10s. 6d. 13s. 6d. 20s. 6d. 6s. 6d. 6 8s. 6d. 11s. 6d. 14s. 6d. 20s. 6d. 7s. 6d. 8 9s. 6d. 12s. 6d. 16s. 6d. 22s. 6d. 10s. 6d. 9 12s. 6d. 15s. 6d. 20s. 6d. 25s. 6d. 11s. 6d. 10 13s. 6d. 16s. 6d. 21s. 6d. 26s. 6d. 13s. 12 17s. 6d. 21s. 6d. 25s. 6d. 30s. 6d. 18s. 6d. The following schedule of prices for borings from the surface from 3 to 12 inches in diameter, are exclusive of lining tubes but include all labour and necessary plant. The prices quoted are per foot. Messrs. Le Grand and Sutcliff. C. Isler and Co. Boring in alluvial and other free- boring Strata. In blowing Sand, Rock, Stone, and other hard or difficult Strata. Gravel, Clay, Sand, or other soft Strata. Rock or Stone. Not exceeding 100 ft. 200 ft. 300 ft. 400 ft. 500ft. 7s. to 14s. 12s. to 24s. 16s. to 30s. 20s. to 40s. 30s. to 50s. 15s. to 50s. 20s. to 70s. 25s. to 70s. 30s. to 80s. 35s. to 90s. 8s. to 20s. 13s. to 30s. 18s. to 40s. 23s. to 50s. 28s. to 60s. 20s. to 40s. 25s. to 50s. 30s. to 60s. 35s. to 70s. 40s. to 80s. The wrought-iron, lap-welded, steel-socketed tubes vary in price with the fluctuations of the market, but the following are recent estimates : Y 322 WATER SUPPLIES 3 -inch internal diameter, | inch thick, 4s. per foot. 4 5s. 6 ,, ,, yV 9s. to 10s. 7| ,, ,, ,, ,, 11s. to 13s. 8|-inch diameter and -^ inch thick, 15s. to 17s. 10 ,, ,, ,, ,, 18s. to 20s. 11| ,, ,, I 23s. to 25s. The approximate depth at which water may be reasonably expected to be found, and the nature of the strata to be pene- trated, being known, the cost of constructing a bored well can be ascertained from the above data. An estimate of the amount of water which the well will yield can only be given by those who have made a special study of the hydrology of the district. The table on p. 323 gives the details of a number of typical wells bored during recent years by Messrs. Le Grand and Sutcliff. As the temperature of the earth's crust increases as we descend, it follows that water taken from a great depth must have a higher temperature than water from shallower wells- The increase in temperature has been found to vary somewhat considerably in different localities, but 1 F. for every 50 to 60 feet descended is a fair average. A well 1000 feet deep, therefore, may be expected to yield a water having a tempera- ture 16 to 20 higher than that of the subsoil water in the same locality, so warm in fact as to be decidedly unpalat- able. In some countries the water obtained is quite hot. Thus, in Queensland, some of the recently sunk deep bores yield waters having a temperature of from 162 to 175 F., the average of a number of wells being over 100 F. In all cases, before deciding upon boring for water, an expert hydro -geologist should be consulted, otherwise the experiment may prove a costly failure. Even the most experienced expert may at times be at fault. Neither the quality nor the quantity of water obtainable can be invari- ably predicted. The supply obtainable may be increased in various ways. By driving two or more tubes, and con- WELLS, AND THEIR CONSTRUCTION 323 Os 00 1 CO i 1 ?o O^OOCO-^frHl-N. O5 CO "ir- OOCOOOOOOOCOOOOO CO X>OO CO COOOOOOOOOOOOO OO CO CO OO 00 OO OO 11 OO T-^l I 1 I ( I 1 I 1 r 1 I I i 1 I-H If bO O rH O O O O O OOOO O & 1 00^0 o oooo oc oogo ooooo os ? S ^> p^o oooo -2? CO O Tt 1 W Tf "^t 1 O CO O C^l O ^^ S l " -l O C^ "^ O O tg i-i'i^ ^ (M(M COi-H rH >^ 1 p (^ (^J tf3 - "" (M a b . 5 ^ " - 1? CO CO CO ** OO l^- t>- 1-- OO OO 1~- Tji CO (M (M OO 00 o tl fcCOQ O'O IO CNOOOiOlOlOO CO Ift IO i-H r-l rH i-l I-IT-H T-I CO O 00 C , ' J "~O 2 5 ^ 5 fi 3 M r-4 OQ i ^ .1 fl'l J3 s ? ^-1 - - - o g " o ^o &, g^ r/) ^ ^ ^ p^ 1 j e > bo O) f Ii * 1 1 iiil i |&filfe ^ 1 | 0,g.g5c OS ^ R-tJrirt-(J -I'oSgs^sl s ^m ^1 J .J "? r ~'~ 1 '"ij i-^5 IT^ -*^ ? t> > t^ ^^^OT-HOQI^-J^-I^- P* M cc* 2 *"* ** 324 WATER SUPPLIES O ! T-^OOOOOOOOO 33 O ffia ! oooooooo_r fcl o .0 j OOOVOOOOO-* ^ 2^O I .22 g o ^ . -S J 12 250 150 2000 j j 12 400 100 3200 Maker C. 10 240 50 1920 j j 12 240 100 1920 Maker D. 10 210 to 300 100 1680 to 2400 10 300 to 450 50 to 60 2400 to 3600 i i 12 300 to 500 100 2400 to 4000 30 7000? 150 Expressed in terms of h.p., a 10-foot mill will give |-1 h.p., a 12- foot mill 1-li h.p., a 14-foot mill 1^-2 h.p., a 16-foot mill 2-2 h.p., an 18-foot mill 2^-3 h.p., and a 20-foot mill 3-4 h.p. Estimates by different makers for pumping engines of various kinds can readily be obtained, but in consider- ing those for wind engines it must be remembered that the storage capacity required is much larger than with any other 344 WATER SUPPLIES form of engine, and therefore increases the initial expense. Where a larger supply than 20,000 gallons per day is required, a steam or gas engine is probably in all cases preferable, but for raising smaller supplies the possibility of utilising the wind as the motive power is always worthy of serious consideration. Water Power. Running water, when available in sufficient quantity, is one of the cheapest and most manageable sources of power for pumping purposes. It may be utilised by means of water-wheels, turbines, or rams, the choice often depending on the fall which can be utilised, the amount of water to be supplied, and the height to which it has to be raised ; but in some cases, where any form is applicable, the selection will be influenced by minor considerations. Whilst water-wheels and turbines are occasionally used for pumping large quantities of water, rams are rarely used when more than 10,000 gallons a day have to be raised. As the hydraulic ram, where it can be utilised, is probably the simplest and cheapest, it may be considered first. Its construction will be rendered intelligible by the follow- ing section and description (Fig. 22). In this ram it is obvious that the water working the ram is the same as that which enters the rising main, and as the proportion of water raised to that wasted is invariably small, its utility is somewhat limited. Recently, however, a double-acting ram has been devised, whereby an impure water by its fall is caused to pump water from a purer source. As yet these are not in general use. These self-acting pumps work day and night, and if by a good maker, and properly adapted for the work they have to perform, the amount of attention and repair required during the year is remarkably little, as there are no parts requiring packing or lubricating. With a reservoir holding sufficient to meet one or two days' demand, repairs, when necessary, can be effected without interfering with the supply. Where large quantities of water are being pumped, a duplicate ram is desirable. PUMPS AND PUMPING MACHINERY 345 The smallest fall which can be utilised is about 18 inches ; the greater the fall the larger the proportion of water, and the greater the height to which it can be raised. Although falls of 40 feet are sometimes used, the wear and tear conse- quent upon the friction and shock necessitates the use of specially-constructed rams. Special rams are also made which will lift water a height of 800 feet, and the water so FIG. 22. A is the feed pipe -communicating with the reservoir supplying the water, B the escape valve, C the valve leading to the air-vessel, D, E is the rising main. When water is admitted to A, it at first escapes through the valve B, which opens downwards, but as the maximum velocity is reached the force is sufficient to close the valve. The flow being suddenly stopped, the pressure rises, and lifts the valve C, which opens upwards, a certain amount of water entering the air-vessel D. The pressure being relieved by the recoil, both valves fall. The water again escapes at B, and the action described is repeated. The intermittent flow into C is converted by the compressed air into a constant flow through the rising main E. raised may be caused to act upon a second ram and raise a portion of the water to a height of 1500 feet. Rams, however, are rarely used to lift water to more than 150 to 200 feet, as the amount of water wasted compared to that supplied increases with the elevation, but more rapidly than the elevation on account of the increased friction. A ram of best construction will raise water thirty times the height of 346 WATER SUPPLIES the fall, but it is not safe to depend upon delivering it at more than twenty-five times the height. Where the water supply is not sufficient to work a ram continuously, it may often be dammed up and discharged at intervals by a syphon arrangement, the ram then working intermittently. Theoretically, disregarding friction, the product of the amount of water falling in a given time into the fall should be equal to the product of the amount raised into the height. Thus 100 gallons falling 10 feet would raise 10 gallons 100 feet, 20 gallons 50 feet, or 100 gallons 10 feet, etc. Friction and imperfections in construction, however, render such a degree of efficiency unattainable'; but some of the best of most modern rams have reached over 80 per cent of efficiency, even with a rising main of considerable length and when the water was being lifted over 100 feet. The smaller the fraction expressed by the ratio of the fall to the height raised, the less the efficiency. Tables giving the efficiency for different ratios have been published, but they are quite useless. Thus in a table recently issued the efficiency of a ram with a ratio of fall to height of T \r is given as 37 per cent, whilst more than one English maker will guarantee at least 50 per cent, and 69 per cent has been attained. Allowing for the friction in a moderate length of rising main, a good ram properly fixed should supply not less than the following percentages of the theoretical amount : Fall. Deree EfficiBiicy citt'ciincd. by Height of Efficiency. Blake's Rams. raised. i * 86 per cent. 76 78 per cent. \ 70 83 66 72 I 63 \ 60 75 \ 58 ; 56 T\F 54 TV 52 69 PUMPS AND PUMPING MACHINERY 347 Example. It is required to know what amount of water can be raised to a height of 100 feet, by a ram working with a fall of 10 feet, the amount of water available being 20,000 gallons per day. Here the ratio -^ should give an efficiency of at least 54 per cent. With perfect efficiency the amount raised would be 2000, since 2000x100 = 20,000x10 and 2000x^^ = 1080, which is the number of gallons per day the ram should be guaranteed to raise to the required height. The efficiency decreases very rapidly when the ratio of the fall to the height raised exceeds J^, so that when -^ is reached the proportion of water pumped to that wasted becomes a very small fraction indeed. In such cases other forms of water motors are preferable ; moreover, with a fall of over 10 feet the wear and tear becomes so very considerable that it is not desirable to attempt to utilise much greater falls with a ram. These conditions, therefore, limit the general usefulness of the ram to situations where the fall of water available is from 1J to 10 feet, and where the supply has not to be raised more than 250 feet. A turbine can often be used where a ram is inadmissible. In the ram the pump is a part of the machine, whereas a turbine is merely a machine for utilising a fall of water to supply the power to work a pump or set of pumps. It follows, therefore, that a turbine worked by a falling stream may be used for pumping water from any source, as from a deep well, and the pumps may be placed at any convenient distance from the source of power, the connection being made by suitable gearing. Any fall from 1 to 1000 feet can be taken advantage of, and there is practically no limit to the depth from which the supply can be raised, or to the height to which it can be propelled. Moreover, they can be so constructed as to work with fluctuating falls and a constant 348 WATER SUPPLIES efficiency of 75 per cent attained. In experimental trials the best turbines have yielded 87 per cent of the actual power of the water, but even with the best makers it is not safe to rely upon more than 75 per cent. The numerous varieties of turbines may be divided into two classes. In the first or " pressure " turbine the falling water is conducted through one or more pipes and allowed to impinge upon the vanes of a wheel, which revolves upon a pivot and is included in a metal case. The impact of the water causes the wheel to revolve with a velocity depending chiefly upon the fall. After expending its energy, the water escapes around the centre of the case. The turbine may be fixed horizontally or vertically, and the vanes may be fixed or movable, the latter only being necessary where the power required or the water available is variable. In the second class of turbines or "impulse" turbines, the falling water (conducted by suitable guides) impinges against a series of "buckets," arranged around the periphery of the wheel. This turbine, therefore, need not be acted upon by the water all round, neither need the wheel be submerged. It must always be fixed at the bottom of the fall, whereas the " pressure " turbine may be placed as much as 20 feet above, the water escaping from the centre passing down a suction pipe and so contributing to the available power. The first form is most generally applicable for low and medium falls, and the latter for high falls. When the supply of water is abundant and a high degree of efficiency is not necessary, cheap forms of the turbine may be employed ; but where it is required to fully utilise the power a machine should be obtained, the high efficiency of which is guaranteed. As large turbines are more efficient than small ones, it is often advisable to store the water during the night and give the whole out during the day to a large turbine, rather than work a smaller machine with the constant flow. On the Continent turbines are much more used than in this country, the largest installation probably being at St. 350 WATER SUPPLIES Maur, where four sets of turbines, each with a diameter of 40 feet, raise over 8,000,000 gallons of water per day to an elevation of 250 feet for the supply of the city of Paris. The fall of water utilised is only 3 feet. The turbines are fixed with the axes horizontal, and are of the "impulse" class. The turbines pumping water for the city of Geneva are of the same description, but work with a fall of 165 feet. Probably the greatest height to which water is raised by any machine is by the turbines pumping water to supply the town of La Chaux de Fonds (population 30,000). These turbines, made by Mons. Escher of Zurich, work with a fall of about 100 feet of water, derived from the Gorges de 1'Areuse, and throw that supplying the town to a height of over 1600 feet. As an example of a village supply the works recently executed at West Lulworth (Dorset) may be cited. The water from a spring on the hillside is piped to a tank placed on a tower immediately over the turbine. The vortex (pressure) horizontal turbine is fixed in a pit 20 feet below the level of the water in the tank. The water falls to the turbine by means of a vertical pipe, the waste water being conveyed away from the bottom by a 12-inch drain and discharged into the sea. From the turbine, which runs about 600 revolutions a minute, the power is communicated by a 10-inch pulley to a larger pulley on the overhead shafting, and thence the power is transferred to a set of three-throw plunger pumps. The machine is estimated to be of 5 h.p., and will lift continuously 1200 gallons per hour into the service reservoir, which is on the hillside, 300 feet above the source of the water. The reservoir has a capacity of 60,000 gallons, and as the population to be supplied is only about 400, it is obvious that the reserve is ample to admit of the pumping being intermittent, and to give time for repairs, etc., to the turbine when such are needed. PUMPS AND PUMPING MACHINERY The efficiency of turbines decreases with the size; hence for small supplies (of from 1000 to 4000 gallons per 24 hours) a small water-wheel, which can be used without gearing, is often more economical, both in first cost and in amount of water used. Water-wheels are too well known to need any descrip- tion. Recently, however, the substitution of light iron wheels for the cumbersome wooden ones previously used has greatly increased the utility of this machine. An " overshot " water- wheel receives the water near the top and has a higher degree of efficiency than either the " high breast," which receives the water above the centre, or the undershot wheel, which receives the water below the centre. Where sufficient fall is available, therefore, the overshot wheel should always be selected. A fall of 1 foot may be utilised for driving an undershot wheel, but not less than 3 feet is required for the over- shot. They are quite as reliable as rams, and as the wheels revolve at a slow speed the shaft can be directly connected with the piston rods of the pumps. Where the water avail- able for working the wheel is variable, an adjustable disc crank can and should be provided, so as to enable the stroke of the pump to be correspondingly varied. The following table gives approximately the amount of water which can be raised per day to a height of 100 feet, with wheels of different diameter and with different supplies of water : Diameter of Wheel. Water Supply per Minute. Quantity raised 100 Feet in 24 Hours. 4 feet. 60 galls. 1,000 galls. 4 100 1,850 4 500 9,250 5 50 1,000 5 100 2,000 5 250 5,000 6 100 2,750 6 500 13,750 These figures refer to an "overshot" wheel. A "high- breast " wheel would raise about 5 per cent less, and an 352 WATER SUPPLIES "undershot " about 15 per cent less, assuming the fall utilised to be the same. As these wheels run night and day, rarely require any attention, are very inexpensive both to purchase and fix, and can be worked by impure water, w r hilst raising a pure water from a well, spring, or other source, it is obvious that under many circumstances they are preferable to a ram, whilst under others they can be used when the ordinary ram is inadmissible. Fuel Engines. Where neither wind nor water are avail- able an engine, deriving its energy from the combustion of fuel (coal, wood, charcoal, petroleum, or gas), must be employed. Such engines differ from those previously described in being a constant expense for fuel and attention ; but the great improvements which have been effected in recent years, especially in the construction of small motors, has prob- ably reduced this expenditure to a minimum. The simplest machines are those which dispense with the use of steam. These are the hot-air, gas, and oil engines. The competition between the makers of these various types of motors, not only amongst themselves, but with the makers of steam engines, has resulted in all being brought to such perfection that it is often a difficult matter to decide which form is the most desirable. The hot-air engine is very compact and economical, requiring but little fuel and skilled attention, but it is only adapted for small works, where the h.p. required is from J to 1. Its only competitor under such conditions is the gas engine, and as this is quite as economical in cost of fuel where gas is reasonably cheap, and requires even less attention, it would probably be selected where gas is available. The gas engine is rapidly supplanting the steam engine in all but the largest pumping stations, since they are not only more compact than steam engines, but, with gas at a reasonable price, more eco- nomical, when the great saving in repairs and in attendance is taken into consideration. When once started they will run for hours without any attention, and there is no risk of explosion from neglect. " Oil " engines are of more recent introduction PUMPS AND PUMPING MACHINERY 353 and, owing to the cheapness of petroleum, are claimed to be more economical than gas engines should the cost of gas be over 2s. per 1000 feet. It is also asserted that the cost of the oil used does not exceed that of the corresponding amount of coal required in driving a steam engine, when such coal can be obtained at 10s. a ton. Where coal is more expensive there is a saving in the cost of fuel, but in all cases there is saved the wages of stoker and driver and the cost of water. As the oil used has a high flashing point there is no risk of explosion, and the danger from fire is reduced to a minimum. In the best machines the vapouriser is heated by a small lamp, taking about 5 to 7 minutes. As soon as the temperature is sufficiently high the engine will start when the jly-wheel is turned. The lamp is then extinguished, since the heat of the vapouriser is afterwards maintained by the continuous explosions. When once started the only attention required is periodical lubrication and the occasional replenishing of the oil reservoir. In fact, after being set in motion it requires no more attention than the gas engine. These engines are now made to work up to 25 h.p., and where gas is not obtainable there is no doubt that they will be extensively employed. In order to enable gas engines to compete with oil engines where there is no public gas supply, plants are now made for converting petroleum oils, fat and grease of all kinds, into gas, and it is claimed that the gas so produced is cheaper than coal-gas. Water-gas may also be manufactured and used for this purpose. As the " oil " engines convert the petroleum into gas in the vapouriser drop by drop as it is required, there does not seem to be any advantage in or any necessity for constructing a gasworks, unless gas. is required for other purposes besides that of supplying the motive power to the engine. Steam engines, except for large waterworks, are not likely to be seriously considered as a source of power on account of the comparatively large expense entailed in labour. For large 2 A 354 WATER SUPPLIES works, however, they continue to be the only practical and efficient motors. In such cases, also, the compound condensing engine will be used. For engines under 10 h.p. the saving effected by the use of a condensing arrangement will not compensate for the additional cost of the engine. The pumps may be driven by a steam engine either directly or through the intervention of a crankshaft and fly-wheel. In the former case the pistons of the cylinder and of the pump are continuous, in the latter the piston of the cylinder acts upon the fly-wheel and the pump piston is attached to the crank. The crankshaft engine requires more space and stronger foundations than the " direct " form, and as the latter are now being made " compounding " and with high duty gear, and are more compact, they will be generally preferred. In calculating the horse power required for pumping a supply of water, the chief factors are : (a) the quantity of water to be raised, and (b) the height to which it has to be lifted or forced. Besides this, an approximate estimate must be made of the power which will be required to overcome the friction due to gearing, and the passage of the water through the pipes. The loss from friction in the pipes will depend upon the nature of the surface of the pipe, degree of smooth- ness or roughness, but more upon the diameter and velocity with which the water is traversing it. It is of the highest importance to have all the mains of sufficient diameter, since the friction increases with the square of the velocity. Thus the friction in a pipe discharging a certain number of gallons per minute will be increased fourfold if the discharge be only doubled. The friction also increases directly as the length of the main. The main should always be of such diameter that the vebcity shall not exceed 2 feet per second (Rawlinson). With this velocity the discharge from pipes of different diameters is given in the following table. It will be observed that the volume for any pipe can be calculated by multiplying the square of the diameter in inches by the volume discharged from a 1-inch pipe. PUMPS AND PUMPING MACHINERY 355 Diameter of Pipe. Volume of Water discharged per Minute with a Velocity of 2 Feet per Second. 1 inch 4'1 gallons. 11 9'2 2. 16-4 3 37-0 4 65-0 6 148-0 8 260-0 10 410-0 12 590-0 j With pipes of such ample diameter the loss from friction is very small and practically negligible. An engine of one 1 actual horse power will raise 3300 gallons 1 foot high per minute, and any smaller quantity to a propor- tionately greater height. From the following simple formula the h.p. required to pump any given quantity of water can easily be calculated : GxH 3300 = H.R, where G = the number of gallons to be pumped per minute and H = the height to which it has to be raised. The allowance for overcoming the friction of the bucket or plunger in the pumps, and of the movement of the water in the pipes, and for raising the piston rods (when pumping from a deep well), cannot be exactly calculated. It is better to err on the safe side and allow 80 per cent for small engines and 40 per cent for larger powers. In all waterworks it is necessary to provide more pumping engines than are actually at any one time required, in order to provide for such contingencies as a break-down or laying- 1 By actual horse power is meant the actual power of an engine given from the shaft or fly-wheel. The term "indicated" horse power, which is frequently used,- is the power given off in the cylinder, and is, of course, higher than the actual or available power. Another term often employed by makers of engines is "nominal" horse power. It is a variable quantity, and so misleading that it should be abandoned. 356 WATER SUPPLIES off for repairs. " In the case of small waterworks it is common to have double the quantity of power needed, in the form of two pumping engines, either of which is capable of doing all the work. The reason for this is that the first cost would probably be rather increased than otherwise, by subdividing the work more, when the engines are very small, even although the total horse power might be less. Then suppose the total horse power needed were six i.h.p. 1 Two engines of six i.h.p. each would probably not cost more than three of three i.h.p. each ; moreover, in work, the efficiency of the one pumping engine of six i.h.p. would be greater than that of the two of three i.h.p. each. Of course there is no hard-and-fast line between small and large works, but it may be very roughly said that it is not advisable to subdivide the pumping power into more than two engines if, by so doing, separate engines of less than ten i.h.p. each have to be provided. In the case of large waterworks, the stand-by power need only equal one- third, one -fourth, or, in the case of very large works, perhaps one-fifth of the whole, there being, in such cases, three, four, or five pumping engines " (Burton, The Water Supply of Toivns). Where engines are employed requiring the use of fuel and attendance, it is desirable to have the machinery of such power that the whole of the water required during twenty-four hours can be pumped in a much shorter time. For mansions, farms, etc., the engines may be sufficiently power- ful to raise in eight or twelve hours as much water as will serve for three or four days, thus necessitating pumping only twice a week. For village water supplies pumping for from four to six hours daily should suffice. For towns up to 20,000 inhabitants the pumps should raise in ten hours the whole day's supply. For larger towns the pumping would probably be continuous. Naturally the h.p. required will have to be regulated by the quantity of water which has to be raised in the given time. 1 Indicated horse power. CHAPTEE XX THE STORAGE OF WATKR WHERE a water supply is derived from the rainfall upon any catchment area, it is obvious that, whether it is to meet the demand of a single house, or of a whole town, sufficient storage must be provided to tide over the longest periods of drought ever likely to occur, and to equalise the supply during a succession of dry seasons. The various ways in which the amount of storage necessary is calculated, and the opinions of various engineers and hydrologists thereon, have already been recorded in Chapter XVII., where the amount of water available from different sources has been considered. The reservoirs used for the above purposes are called " im- pounding" reservoirs, and when of large size they are usually situated in a valley, or at the junction of two valleys, where, by excavation and the construction of a dam, a sufficient quantity of water can be collected. The ground must be first surveyed to ascertain the character of the impervious stratum and its distance from the ground surface. If of rock, its freedom from fissures (common in certain formations), through which the water could escape, must, if possible, be determined. The presence of an undiscovered fissure may result in the reservoir, after construction, having to be abandoned, or in the expenditure of large sums of money in detecting and attempting to remedy the defect. The dam may be of masonry or of earthwork, but the former is only applicable where there is a rocky 358 WATER SUPPLIES foundation. The latter can be constructed on rock, clay, or other impervious strata, and is less costly than masonry. If, however, the water is once able to penetrate it, the channel will continuously increase in size and the dam will be destroyed, whereas defects in masonry dams have not this tendency to continuous increase and admit of being more easily discovered and remedied. All vegetable matter should be removed from the sides and bottom of new reservoirs, otherwise these, by their decomposition, will give up organic matter to the water, favourable to the growth of low forms of life. To draw off the water a valve tower is provided, which admits of valves being opened at various depths, so as to avoid drawing either from too near the surface or too near the bottom. A meter house may be required, in which to fix the apparatus for recording the amount of water which is passing into the mains, or the amount of compensation water being supplied, or both, and a by-pass to allow of flood water being diverted from the reservoir, and to prevent the water rising above a certain level. According to Rawlinson, the outer portion of the embank- ment must be effectively drained, and if there are springs of water in the puddle trench (as there usually are), these must be collected and brought away. No form of culvert or other works for drawing off water should be constructed within or beneath or through the deepest made portion of the bank, but the outlet tunnel, valve chamber, and works connected with the drawing off of the water must be in the solid ground, on the side of the valley. At the centre of the bank the valve chamber should be formed. All pipes and valves should be so placed as to be easily reached for repairs or renewals, and it should be so arranged that no valve in the tier of valves in the valve well need be worked under a greater head than 10 or 15 feet. In cases also where the water is derived from springs and streams of variable flow, the supply sometimes falling below that of the average demand, impounding reservoirs are THE STORAGE OF WATER 359 necessary to equalise the supply. The size will depend upon many circumstances, but will be chiefly influenced by the length of time during which the yield is below the average, and by the extent of the fluctuations. Where river water is impounded it must also be remembered that at certain periods, following heavy rains, the water will be more or less turbid or impure, and may have to be allowed to run to waste. Where the average supply of a stream is more than sufficient to meet all requirements, more or less storage is still required to enable pure water to be supplied whilst the river is in flood and its waters turbid and possibly polluted. Wherever the water collected requires to be filtered before being delivered to the consumer, reservoirs for "settling" are an almost indispensable adjunct to the filter beds. Such " settling " reservoirs retard the clogging of the pores of the sand in the filter beds, and therefore enable the filters to work for longer periods without cleansing. They should be so constructed as to allow of emptying and cleansing, but should not be too shallow, otherwise the water may become unpleasantly warm in summer. A water depth of 12 to 16 feet is usually recommended. As generally constructed, with sloping sides, the growth of algae is favoured. Vertical sides are preferable. Smaller or " service " reservoirs are often also constructed in or near the place to be supplied with water, in order to enable a constant average flow to be maintained to meet the very varying demand during the 24 hours. These are especially necessary where the water has to undergo a process of filtra- tion, in order that the process may be uniformly continuous. Without such a service reservoir, during the period of greatest demand imperfectly - filtered water would pass into the mains, unless filter beds of an otherwise unnecessarily large area had been provided. These reservoirs are also commonly used when water is raised by pumping. Without such storage it is evident that pumping would have to be continuous, and that the rate would have to vary with the 360 WATER SUPPLIES demand, whereas with a service reservoir the pumping engines may work at a uniform speed, and for only a portion of the 24 hours. When the source from which water is derived is at a con- siderable elevation, and long lengths of main convey the water in different directions, as to villages and towns en route to its ultimate destination, service reservoirs are often constructed at elevated points, not only to break the pressure, but to enable smaller mains to be used. Without these reservoirs the mains would have to be capable of supplying the maximum consumption, whereas with storage, the mains, as far as the reservoirs, need only be capable of delivering the average demand. As the maximum hourly consumption may be twice the mean consumption, the difference in first cost, where the mains are of any length, is very considerable. Another very important advantage of such reservoirs is that in case of fire there is a reserve of water instantly avail- able. This is especially valuable in connection with the supply of small towns, villages, mansions, and farms, since the amount of water likely to be used in case of an outbreak of fire would be a large faction of, or might even exceed that of the whole capacity of the mains, whereas in large towns the increased demand would only be a small fraction of the average supply. The amount of storage necessary and its character depends upon the mode of supply, and whether by gravitation or by pumping. Writing of these two classes of waterworks, Burton, in his work on The Water Supply of Toivns, says : Gravitation works to be complete must consist of 1. Either a high-level impounding reservoir, or a high- level intake with a settling reservoir. 2. Filter beds. 3. A service reservoir near the impounding or settling reservoir, or, if there is high land conveniently situated, a reservoir as near as possible to the town THE STORAGE OF WATER 361 or within it, or one or more high-level tanks within the town. 4. A distributing system. " A pumping system may consist of JNIVERSITY A. 1. A comparatively low-level intake. \ Q 2. One or more settling reservoirs. 3. A set of filter beds. 4. A pumping station, with 5. A high-level reservoir or tank near or within the town, holding enough to compensate for the inequality of the consumption during 24 hours. 6. A distributing system. B. Where there is no land for a high-level reservoir, and a high-level tank on an artificial support to hold enough water to compensate for the variation in consumption during 24 hours is considered impracticable. 1. A comparatively low-level intake. 2. One or more settling reservoirs. 3. A set of filter beds. 4. A low-level service reservoir. 5. A pumping station with engines pumping directly into 6. A distributing system. C. When the intake is so low that the water will not gravitate to any convenient place for settling reservoirs and filtering beds, and there is room for these only on low ground. 1. A low-level intake. 2. An intake pumping station with engines pumping into 3. One or more settling reservoirs. 4. A set of filter beds. 5. Main pumping station with engines pumping into 6. A high-level reservoir on a high artificial support, and 7. A distributing system. D. The same as before, C, up to 5, but 362 WATER SUPPLIES 5. A low-level service reservoir. 6. Pumping station, with engines pumping into 7. A distributing system. The last case, as that of B, occurs where there is no natural site for a high-level reservoir, and where a high-level tank of sufficient size on an artificial support would be too expensive, or is, for any other reason, impracticable. Under peculiar circumstances modifications of these systems may be and are adopted, and, of course, when the low-level intake is a well or spring yielding water invariably pellucid, the settling reservoirs and filter beds are dispensed with, and the system is much simplified, the water being forced directly into a high-service reservoir or even into the distributing mains. Impounding reservoirs must be of ample size, not only to meet present demands, but also such increased demand as may arise in the more immediate future. Where large works are being constructed 50 years is not an unreasonable length of time to look forward to, and as a minimum the probable increase in 30 years should be provided for. Many towns have been recently subject to immense inconvenience and anxiety on account of this neglect, or from underestimating the growth of the population and the consequent increased demand for water. The conditions which affect the decision as to the size of settling and service reservoirs are of a different character, but probably the most important is the effect of storage. This varies somewhat with the character of the water ; speaking generally, the purer the water the less the liability to change. In natural reservoirs, or lakes, water is less prone to be infested by organisms, which affect the odour and taste, than in artificially -constructed reservoirs. Pure surface water contains too little organic matter to favour the growth of these algae and fungi, and the effect of storage is beneficial rather than otherwise ; yet cases are recorded where very pure waters have developed an objectionable odour and taste. THE STORAGE OF WATER 363 These growths are usually found to occur in reservoirs storing water collected from gathering grounds which are in part cultivated. The small amount of manurial matter, or the products of its oxidation taken up by the water, supplies constituents necessary to the growth and multiplication of these low forms of life. Peaty water tends to lose its colour if long stored, probably from the action of light, but the observers for the Massachusetts Board of Health, who have very fully studied the effect of storage, found that 12 months' exposure was necessary to completely bleach such water. They found that surface waters, by storing, suffered no change in the amount of ammonia and nitrates present, but in other waters the nitrates were slightly reduced. Investi- gating waters taken from various depths from a deep but small lake, they concluded that vertical circulation took place during the winter months, but that during the summer this was in abeyance, and that the water at the bottom of the lake remained stagnant. When the air is colder than the water, the surface of the latter will cool, becoming at the same time denser and tending to sink ; when the air is warmer than the water, or the latter is exposed to the direct action of the sun's rays, the surface will become heated, and, decreasing in density, will retain its position. This, of course, applies to water stored in large or small reservoirs, provided the water is exposed to the air. The result of the stagnation is probably very slight in waters of great hygienic purity, but in waters containing organic matter the free oxygen disappears, the water deteriorates, free ammonia increasing in amount, especially at depths below 20 feet, and at such times samples of water from near the top and near the bottom may yield very different results upon analysis. Ground water when stored in open reservoirs is said to "deteriorate at all seasons of the year." The albumenoid ammonia, or rather the organic matter yielding ammonia upon distillation with alkaline permanganate, increases, and in spring and summer the free ammonia becomes excessive, 364 WATER SUPPLIES and at the same time nitrates are reduced. The micro- organisms, which in the water at its source are few in number, increase rapidly, so that they may even be in excess of those found in much more impure waters. The same water when kept in covered tanks is said to suffer but an inappreciable change ; this is attributed to the absence of light and the difficulty of access of air -conveyed microbes. I have fre- quently observed, however, that the waters taken from a whole series of wells over a definite area yielded much better results both chemically and bacteriologically when examined in winter than when collected in summer. In small open tanks through which water is constantly passing, the water undergoes, as a rule, but little change, but numerous instances are recorded of the rapid and persistent growth of organisms even in service tanks. This is almost certainly prevented by thoroughly cleansing and covering the tanks. One organism, however, grows better in the dark than in the light, the " Oenothrix," and occasionally gives rise to trouble by im- parting a nauseous odour and taste to the water. As this fungus requires for its growth both protoxide of iron and organic matter, a water in which it can nourish is not desirable for a domestic supply. The results of all the observations which have been made on storage as affecting the size of service reservoirs lead to the conclusion that it is desirable to reduce this storage to the minimum compatible with safety. It is only necessary, therefore, to consider what capacity is required for compen- sating for the inequality of the hourly consumption, and for a reserve in case of fire. Inequality of Hourly Consumption. Whilst the maximum consumption for a whole month rarely exceeds by 30 per cent the mean for the year, the maximum hourly consumption may exceed this by 100 per cent. Mr. J. Parry, M.Inst.C.E., found in Liverpool during 1893 that the maximum weekly consumption took place in July, when it was 15 per cent above the mean, and that the minimum occurred in November THE STORAGE OF WATER 365 and December, and was 9 per cent below the mean. The highest hourly rate at which water was delivered was between 10 and 11 A.M. on 6th July, when the delivery- was at the rate of 50 gallons per head, or 85 per cent above the average for the year. Mr. Parry says, " The weather at the time was exceptionally warm, and it is not probable that the differ- ence between the mean and maximum rate of discharge could ever exceed this amount." Experiments which have been conducted in Germany, however, have shown a greater variation than this. Taking the mean of a number of records from various waterworks, and taking the mean annual con- sumption as 1 '0, the maximum daily discharge was 1 '4, and the maximum hourly 2*1. The minimum flow is of trifling importance ; in nearly all cases where waste is prevented as much as possible, the flow during some portion of the night approaches zero. It is easily demonstrated that a service reservoir capable of holding 7 hours' mean supply would be amply large to com- pensate for all inequalities in the demand for ordinary purposes, but in small towns this would be but a small reserve in case of fire. Reserve for Fire Extinction. In many cases little reserve for this purpose is required, since by means of a by-pass or by increased pumping all the necessary water may be rendered available. Where such is not the case Burton gives a formula for estimating roughly the amount of water which should be stored for the special purpose of fire extinction : Q = 200VP, where Q = the quantity to be stored in cubic feet and P the population of the town. This formula gives 125,000 gallons as the storage for this purpose in a town of 10,000 population, and 1,250,000 for a city of 1,000,000 inhabitants, or 10 hours' mean supply for the former and 1 hour for the latter. To compensate for the inequalities in the demand for domestic purposes and for use in case of fire, 1 7 hours' storage 366 WATER SUPPLIES in the smaller town and 8 hours in the latter would suffice. In any case 1 day's supply should be ample. This is a reasonable mean between the estimates of those who recommend 6 or 7 hours' storage and those who would provide 2 or 3 days' storage. Where such an amount cannot be kept in reserve the pumping machinery must be sufficiently powerful to supply the additional quantity, or if the water flows by gravitation from impounding reservoirs the service mains must be large enough to carry it. In moderate-sized towns the service reservoir may be placed upon an elevated tower of brick, stone, or ironwork. The tank should be constructed of wrought or cast iron, covered to exclude light, heat, and dust, and it should be divided into two or more compartments for convenience in cleansing. Where placed upon a natural elevation it may be of brickwork rendered in cement. In larger towns, where there is no elevated ground sufficiently near, and the erection of tanks on towers would be too expensive, storage must be dispensed with, and the mains, if a gravitation system, must be sufficiently large to supply the maximum demand ; or if a pumping system, the pumping engines must be so constructed that the pumping corresponds exactly with the consumption. A constant pressure may be obtained from a stand pipe or by means of an air chamber. A float within the stand pipe can be made to adjust the speed of the engine or the stroke of the pumps, decreasing when the water rises and increasing when the water falls, or the pressure in the air chamber may be caused to automatically check or accelerate the action of the pumps. In Chapter II. reference was made to the storage of rain water for the supply of cottages, farms, and mansions. Denton recommends that the tanks used should be capable of holding 120 days' supply, but few mansions or farms have sufficient roof area to allow of anything like this quantity being collected even in the wettest seasons, whilst the average cottage could not collect more than half this amount. A THE STORAGE OF WATER 367 tank capable of holding one-third of the rainfall is probably as large as ever could be filled, and it is useless constructing tanks to hold more water than can be collected, and absurd to think of compensating for a too limited collecting area by increasing the storage capacity. Only the excess of rainfall over and above that used during the rainy season can be stored, and the smaller the collecting areas, the smaller will be the surplus and the smaller the tank which is necessary for storing it. Rain-water tanks are usually placed underground, where it is almost impossible to ascertain if they are water-tight. They are difficult of access and more difficult to cleanse. Tanks fitted with rain-water separators and filters can be con- structed above ground, and are in every respect preferable. Underground tanks, if cut out of solid chalk or sandstone, merely require lining with cement. Tanks constructed in pervious soil must be made of brickwork in cement and be rendered in cement, and arched over with the same materials. Where water has to be pumped for single houses or small groups of houses, in calculating the amount of storage necessary it must be remembered that the inequalities in the demand will vary to a much greater extent than when a whole village or town is being supplied. For this reason the tank must be larger in proportion, and also because provision must be made for such contingencies as the breakdown of the pump- ing machinery and an outbreak of fire. A comparatively small quantity of water at the moment when a fire is discovered may suffice to prevent a conflagration ; hence, if possible, some provision should be made to render a supply readily available. It has already been pointed out that water tends to deteriorate in quality when stored in tanks ; therefore it is better, if possible, to have a separate reservoir for storing water for fire extinction. Where valuable property is con- cerned, as in mansions and large farms, the additional expense incurred may prove a valuable investment. The size of tank required if the water is to be utilised for all purposes will 368 WATER SUPPLIES depend upon (1) the amount desired to be stored in case of fire ; (2) whether the pumping is constant, as by a ram, turbine, or water-wheel, or (3) intermittent and at irregular intervals, as when the ptiinps are worked by a wind engine, or (4) inter- mijjftrii; but at regular intervals, as when manual labour or sdme form, of gas, oil, hot-air or steam engine is used. Leaving (1) out of consideration, with the second or fourth arrange- ment a tank holding 2 to 4 days' domestic supply would be ample. With the third system there should be storage provided for from 7 to 1 2 days' supply. If the same tank is required to store water for fire extinction, it must be larger, according to the quantity considered necessary for use in such an emer- gency. Where there is an ample amount of water at the intake and a steam or similar engine is used for pumping, the fire reserve needs not be large, since the engines can speedily be set to work and the reserve supplemented. The possibility of water being injuriously affected by the materials of which small tanks are often made has been mentioned in Chapter IX., and the advantages and disadvan- tages of storing water in house cisterns, necessitated by an " intermittent " public supply, will be referred to in the next chapter on "The distribution of water." Where the water supply is "constant," there should be no necessity for storage cisterns in private houses. But where the supply is only " constant " in theory, and not in actual practice, as in many parts of London during seasons of drought, these cisterns must be retained ; but in such cases draw-off taps should be affixed to the rising main for the supply of water for dietetic purposes. Of course this cistern should not directly supply any water-closet or place of similar character. Where the water supply is " intermittent," a storage cistern capable of holding one day's supply is absolutely necessary. CHAPTEE XXI THE DISTRIBUTION OF WATER IT is now generally admitted that no public supply is entirely satisfactory unless the mains are constantly full and under pressure that is, unless the supply be " constant." Under the mistaken impression that the amount of water supplied would be economised, most of the older waterworks only admitted water to the mains for one or more hours daily, during which time the house cisterns were filled, and the amount used in each house was limited by the capacity of its cistern. This " intermittent " system is now being gradually abandoned, since, as we have already seen, a constant supply when properly superintended is equally, if not actually more economical. The risk of the water becoming polluted in the mains (vide Chapter XL) is also reduced to a minimum by keeping them constantly full and under pressure, and in case of fire a supply of water is more readily available. As the whole day's supply has not to be delivered in a very few hours, the mains need not be so capacious, and house cisterns are no longer necessary. The disadvantages of such cisterns are numerous. Usually placed in inaccessible situations, un- covered or imperfectly covered, and constructed of unsuitable material, they are a frequent cause of the water becoming fouled, or of its becoming unpalatable from the heat, and a severe frost is more likely to cut off the supply. For these reasons no engineer would now suggest the adoption of the " intermittent " system, and it is to be hoped that where 2B 370 WATER SUPPLIES adopted it will soon be abandoned, and that every house over the areas supplied will have a constant service at high pressure. Whilst open conduits may convey water from the intake to the filter beds, covered conduits or cast-iron pipes must be used for carrying water from the filter beds to the service reservoirs. Where the pressure is but slight earthenware pipes may be used, or masonry, or brickwork, but iron will probably be cheaper than the latter. For such aqueducts a fall of 5 feet per mile will suffice for pipes of 2 feet in diameter, and a fall of 17 feet should not be exceeded. Earthenware pipes are not desirable, but if used must be laid in a well-puddled or concrete-lined, water-tight trench, and if valleys have to be crossed the syphon portion must be of cast iron to with- stand the pressure, and means should be provided to wash out the syphon at its lowest point. In pumping mains the velocity of the water should be about 2 feet per second, and in no case exceed 2 \ feet. To allow for growth of population, increased demand and corrosion of pipes, a velocity of 1 \ feet in the first instance will probably be as large as can be adopted with safety. (The power expended in pumping varies directly as the cube of the velocity ; hence, what is saved by using smaller pipes is more than lost in the cost of power.) In gravitation mains a little higher velocity, 3 feet per second, is permissible. For calculating the velocity with which water will pass through cast-iron mains when first laid, Eytelwein's formula is fairly reliable : V = ttV/" dh where V = the velocity in feet per second ; d, the diameter of the pipe ; h, the head of water ; and I, the length of the pipe in feet. In new pipes ft = 50, but its value decreases with the corrosion, and may sink as low as 32. The factor 50c? may be disregarded in pipes more than a few hundred feet in length. Sharp bends should be avoided, since they THE DISTRIBUTION OF WATER 371 increase the friction and retard the flow. Where the pipes follow the contour of the ground, air-valves should be attached to the highest points. All pipes used should have previously been tested and proved to be capable of withstanding twice the pressure to which it is calculated that they will be subjected. A "trunk" main conveys the water from the service reservoir to the confines of the districts to be supplied. It then breaks up into "distributing" mains, one for each dis- trict. The "distributing" mains supply "service" mains, and from these latter are taken the "house service " mains or " communication pipes." No service main should be less than 3 inches in diameter, and in towns it is never desirable that they should be less than 4 inches. In many American cities the minimum is 6 inches. For the sake of economy mains of too small diameter are frequently employed, and the mistake when discovered is a costly one to remedy. A common error is to suppose that the flow of water varies only with the sectional area of the main, but a glance at Eytelwein's formula is sufficient to disprove this. For example, with a head of 100 feet and a main 10,000 feet long, what will be the flow from a 3-inch and a 6-inch main respectively? In the first case V = 50 V'25"x 100 = 2-5 feet per second, 10,000 and the flow = V x ^-'7854= '1227 cubic feet per second. In the second case V = 50 V'5 x 100 3'5 feet per second, To, ooo and the flow will be '687 cubic feet per second. The loss of head on account of friction is a still more serious matter when it is intended that the water shall be available for fire-extinguishing. Thus, to quote an example from Merry weather's Water Supply to Mansions : " The passage of 300 gallons of water per minute through 500 372 WATER SUPPLIES yards of 4-inch pipe will absorb in friction a head of 172 feet, whereas if 5-inch pipe be used, only 57 feet will be absorbed ; that is, assuming the reservoir to be 200 feet above the house, if you lay the 4-inch pipe 500 yards long, when delivering 300 gallons per minute the head or pressure on the jets will only be 28 feet, .and the height of the jets about 20 feet, but with the 5-inch pipe the head will be 143 feet, and the height of the jet will be 100 feet ; in each case the balance of the 200 feet is absorbed by the friction of the water against the sides of the pipe." In certain towns Liverpool, for instance special mains are laid through the business parts for supplying water for extinguishing fires. In the residential parts the same mains act as fire mains as well as service mains. Cast-iron pipes are practically universally used for distribut- ing and service mains, and these should be properly varnished within and without. This varnish generally imparts to the water, for a time, a tarry flavour, which, although objection- able, is not injurious. After long keeping the varnish imparts less flavour to the water, but pipes so kept are not so durable as those laid down soon after being coated. Turned and bored joints are cheapest, but engineers are divided in opinion as to whether these or joints made with lead are the best. The latter are more flexible, and should alone be used where the ground is not firm . or where there is danger of subsidence. Where turned and bored joints are used, an occasional lead joint should be introduced to allow for the elongation and contraction caused by changes of temperature. To prevent the undue influence of the variations of the earth's temperature, Rawlinson says that the mains should be laid at a minimum depth of not less than 3 feet. Other engineers give 2 feet 6 inches as the minimum, but in England the water in mains at the latter depth has become frozen during very severe winters. The latter is the depth of cover required in most large towns, but in Manchester 3 feet, and in Bradford 2 feet is adopted as the minimum. THE DISTRIBUTION OF WATER 373 In all systems of distribution it is not only of the highest importance to have all the mains of ample size, but that the service mains be so arranged that there shall be few or no "dead ends," and that, as far as possible, all valves and connections should be placed so that in case of accident to one main the supply may be kept up from another. The "dead end" system had many apparent advantages which caused it to be generally used. Parts of the system could easily be cut off when necessary by a single valve, and the sizes of the mains could be readily calculated. It was soon found, however, that the stagnant water in the ends became deteriorated in quality, and it has sometimes been suspected that where disease germs had gained access to the mains they had been able to multiply in the still water. This can in part be prevented by placing flushing valves at the ends of the mains, but these require constant attention, and if regularly opened cause the waste of much water. On the whole it seems preferable to adopt some form of inter- lacing system, in which the ends of the mains are connected together, wherever possible. By a proper arrangement of sluices any small portion of the system can be cut off by closing two valves, whenever such closure is necessary for the repair of that portion. Formerly the supply to a district had to be stopped every time the main was being tapped, but ferrule machines have been constructed and are now largely used, which enables the " house service " mains to be attached to the service mains whilst the latter are full of water under pressure. Where this machine is used the occasions upon which it is necessary to cut off any part of the system are very rare. It is obvious that water- waste preventors, such as Deacon's, cannot be used on any portion of the interlacing system. They must be attached to near the ends of the distributing mains, and each controlled by a valve beyond the meter, and there should be a separate distributing main for each district of from 2000 to 5000 people. 374 WATER SUPPLIES House service pipes may be of lead, tin-lined lead, tin-lined iron, cast iron or wrought iron, enamelled or galvanised. Lead pipe is most generally applicable, but it should not be used with waters which contain very little or no carbonates. Such waters are usually very soft, but it is desirable to remember that occasionally very soft waters contain car- bonate of soda and have no action on lead, and that hard waters sometimes are free from carbonates and then act upon this metal. To prevent this action tin-lined lead pipe was introduced, but has not answered the expectations of its makers. It possesses little advantage over lead pipe, and has many disadvantages, besides being much dearer. Still more recently a tin-lined iron pipe has been placed in the market, and so far as present experience enables its merits to be appraised, it would appear to possess many advantages over all other kinds of pipe. It consists of strong wrought-iron tube with an internal lining of block tin, and the lengths are joined up by screw joints, so that the tin lining is practically continuous. Wrought-iron pipes are cheaper than lead, and as easily or more easily fitted, and admit of repairs and alterations being made with equal facility, provided double screw joints are used at convenient points. They are, however, very liable to become choked by internal corrosion. A pipe 1 inch in diameter may choke in from six to ten years. If galvanised its durability is much increased. Certain soft waters, however, possess the power of dissolving zinc, and of rapidly corroding the iron. In such a case the tin-lined iron pipe becomes indis- pensable, since the same waters invariably act upon lead. Where water pipes have to be carried through made ground containing ashes, spent lime, chemical refuse, etc., they should be protected by a clay puddle, concrete, or asphalte covering, otherwise they will be injuriously affected. To prevent the action of frost a minimum depth of 3 feet is desirable, and within the house they should be placed in positions in which the frost is least likely to affect them. No THE DISTRIBUTION OF WA TER 375 pipe will withstand the action of frost, but lead pipes may usually be frozen many times before actually bursting, on account of the ductility of the metal. The split caused by the expansion of the water in the act of freezing is in all cases longitudinal. In lead pipe the metal bulges before splitting. As it is of the highest importance for the pre- vention of waste and pollution that all house connections should be properly made, and the fittings be of a satisfactory character, the regulations made under the " Metropolis Water Act, 1871," as to house fittings, are given in an appendix, as upon them are based the regulations of many other towns. Mr. T. Duncanson, in his paper, already referred to, on " The Distribution of Water Supplies," gives the following brief summary of the objects to be aimed at in providing a public supply of water : "(1) That a sufficient supply of wholesome water for the reasonable needs of a community should be provided. "(2) That this water should be so supplied that at all times there is sufficient pressure to reach the highest part of every house. " (3) That all piping and fittings should be of such a character and so arranged as to reduce the probability of failure to a minimum. " (4) That there should be an effective system for the prompt detection of waste when it does occur. " (5) That all arrangements should be of such a character as to reduce the inconvenience arising from necessity for repairs to a minimum. " (6) That all appliances for the consumption of water should be so arranged as to use it in the most efficient way. "The extent to which a public supply meets the above requirements will be a fair index of its character." APPENDIX TO CHAPTER XXI REGULATIONS MADE UNDER THE METROPOLIS WATER ACT, 1871 1. No " communication pipe " for the conveyance of water from the waterworks of the Company into any premises shall hereafter be laid until after the point or place at which such "communication pipe" is proposed to be brought into such premises shall have had the approval of the Company. 2. No lead pipe shall hereafter be laid or fixed in or about any premises for the conveyance of, or in connection with the water supplied by the Company (except when, and as otherwise authorised by these regulations, or by the Company), unless the same shall be of equal thickness throughout, and of at least the weight following, that is to say : Internal Diameter of Pipe in inches. Weight of Pipe in pounds per lineal yard. i in 4 > i- , ch dian > icter 5 Ibs. pe 6 74 r linea . yard ? , i u , i 9 , 12 16 3. Every pipe hereafter laid or fixed in the interior of any dwelling- house for the conveyance of, or in connection with, the water of the Company, must, unless with the consent of the Company, if in contact with the ground, be of lead, but may otherwise be of lead, copper, or wrought iron, at the option of the consumer. 4. No house shall, unless with the permission of the Company in writing, be hereafter fitted with more than one "communication pipe." 5. Every house supplied with water by the Company (except in APPENDIX TO CHAPTER XXI 377 cases of stand pipes) shall have its own separate "communication pipe," provided that, as far as is consistent with the special Acts of the Company, in the case of a group or block of houses, the water-rates of which are paid by one owner, the said owner may, at his option, have one sufficient "communication pipe" for such group or block. 6. No house supplied with water by the Company shall have any connection with the pipes or other fittings of any other premises, except in the case of groups or blocks of houses, referred to in the preceding regulation. 7. The connection of every "communication pipe" with any pipe of the Company shall hereafter be made by means of a sound and suitable brass screwed ferrule or stop-cock with union, and such ferrule or stop-cock shall be so made as to have a clear area of water-way equal to that of a half-inch pipe. The connection of every "communica- tion pipe " witli the pipes of the Company shall be made by the Company's workmen, and the Company shall be paid in advance the reasonable costs and charges of, and incident to, the making of such connection. 8. Every "communication pipe" and every pipe external to the house, and through the external walls thereof, hereafter respectively laid or fixed in connection with the water of the Company, shall be of lead, and every joint thereof shall be of the kind called "plumbing" or "wiped " joint. 9. No pipe shall be used for the conveyance of, or in connection with, water supplied by the Company, which is laid or fixed through, in, or into any drain, ash-pit, sink, or manure-hole, or through, in, or into any place where the Avater conveyed through such pipe may be liable to become fouled, except where such drain, ash-pit, sink, or manure-hole, or any such place, shall be in the unavoidable course of such pipe, and then in every such case such pipe shall be passed through an exterior cast-iron pipe or jacket of sufficient length and strength, and of such construction as to afford due protection to the water pipe. 10. Every pipe hereafter laid for the conveyance of, or in connection with, water supplied by the Company, shall, when laid in open ground, be laid at least 2 feet 6 inches below the surface, and shall in every exposed situation be properly protected against the effects of frost. 11. No pipe for the conveyance of, or in connection with, water supplied by the Company, shall communicate with any cistern, butt, or other receptacle used or intended to be used for rain water. 12. Every "communication pipe "for the conveyance of water to be supplied by the Company into any premises shall have at or near 378 WATER SUPPLIES its point of entrance into such premises, and if desired by the consumer within such premises, a sound and suitable stop- valve of the screw- down kind, with an area of water-way not less than that of a half-inch pipe, and not greater than that of the "communication pipe," the size of the valve within these limits being at the option of the consumer. If placed in the ground such "stop- valve" shall be protected by a proper cover and "guard-box." 13. Every cistern used in connection with the water supplied by the Company shall be made and at all times maintained water-tight, and be properly covered and placed in such a position that it may be inspected and cleansed. Every such existing cistern, if not already provided with an efficient "ball-tap," and every such future cistern, shall be provided with a sound and suitable "ball-tap" of the valve kind for the inlet of water. 14. No overflow or waste pipe other than a "warning pipe" shall be attached to any cistern supplied with water by the Company, and every such overflow or waste pipe existing at the time when these regulations come into operation shall be removed, or at the option of the consumer shall be converted into an efficient "warning pipe," within two calendar months next after the Company shall have given to the occupier of, or left at the premises in which such cistern is situated, a notice in writing requiring such alteration to be made. 15. Every " warning pipe " shall be placed in such a situation as will admit of the discharge of the water from such "warning pipe" being readily ascertained by the officers of the Company. And the position of such "warning pipe" shall not be changed without previous notice to and approval by the Company. 16. No cistern buried or excavated in the ground shall be used for the storage or reception of water supplied by the Company, unless the use of such cistern shall be allowed in writing by the Company. 17. No wooden receptacle without a proper metallic lining shall be hereafter brought into use for the storage of any water supplied by the Company. 18. No draw-tap shall in future be fixed unless the same shall be sound and suitable and of the " screw-down " kind. 19. Every draw-tap in connection with any "stand pipe" or other apparatus outside any dwelling-house in a court or other public place, to supply any group or number of such dwelling-houses, shall be sound and suitable and of the " waste - preventer " kind, and be protected as far as possible from injury by frost, theft, or mischief. 20. Every boiler, urinal, and water-closet, in which water supplied by the Company is used (other than water-closets in which hand flushing is employed), shall, within three months after these rcgula- APPENDIX TO CHAPTER XXI 379 tions come into operation, be served only through a cistern or service-box and without a stool-cock, and there shall be no direct communication from the pipes of the Company to any boiler, urinal, or water-closet. 21. Every water-closet cistern or water-closet service-box hereafter fitted or fixed, in which water supplied by the Company is to be used, shall have an efficient waste-preventing apparatus, so constructed as not to be capable of discharging more than two gallons of water at each flush. 22. Every urinal-cistern in which water supplied by the Company is used other than public urinal-cisterns, or cisterns having attached to them a self- .-dosing apparatus, shall have an efficient "waste- preventing" apparatus, so constructed as not to be capable of discharging more than one gallon of water at each flush. 23. Every "down pipe" hereafter fixed for the discharge of water into the pan or basin of any water-closet shall have an internal diameter of not less than one inch and a quarter, and if of lead shall weigh not less than nine pounds to every lineal yard. 24. No pipe by which water is supplied by the Company to any water-closet shall communicate with any part of such water-closet, or with any apparatus connected therewith, except the service-cistern thereof. 25. No bath supplied with water by the Company shall have any overflow waste pipe, except it be so arranged as to act as a " warning pipe." 26. In every bath hereafter fitted or fixed the outlet shall be distinct from, and unconnected with, the inlet or inlets ; and the inlet or inlets must be placed so that the orifice or orifices shall be above the highest water-level of the bath. The outlet of every such bath shall be provided with a perfectly water-tight plug, valve, or cock. 27. No alteration shall be made in any fittings in connection with the supply of water by the Company Avithout two days' previous notice in writing to the Company. 28. Except with the written consent of the consumer, no cock, ferrule, joint, union, valve, or other fitting, in the course of any "communication pipe," shall have a water-way of less area than that of the "communication pipe," so that the water-way from the water in the district pipe or other supply pipe of the Company up to and through the stop- valve prescribed by Regulation No. 12, shall not in any part be of less area than that of the "communication pipe" itself, which pipe shall not be of less than a half-inch bore in all its courses. 29. All lead " warning pipes " and other lead pipes of which the 380 WATER SUPPLIES ends are open, so that such pipes cannot remain charged with water, may be of the following minimum weights, that is to say : ^ inch (internal diameter) . . 3 Ibs. per yard. f ,, ,, 5 Ibs. ,. 1 ,, 7 Ibs. ,, 30. In these regulations the term "communication pipe" shall mean the pipe which extends from the district pipe or other supply pipe of the Company up to the "stop- valve" prescribed in the Regulation No. 12. 31. Every person who shall wilfully violate, refuse, or neglect to comply with, or shall wilfully do or cause to be done any act, matter, or thing, in contravention of these regulations, or any part thereof, shall, for every such offence, be liable to a penalty in a sum not exceeding 5. 32. Where, under the foregoing regulations, any act is required or authorised to be done by the Company, the same may be done on behalf of the Company by an authorised officer or servant of the Company, and where, under such regulations, any notice is required to be given by the Company, the same shall be sufficiently authenticated if it be signed by an authorised officer or servant of the Company. 33. All existing fittings, which shall be sound and efficient, and are not required to be moved or altered under these regulations, shall be deemed to be "prescribed fittings" under the "Metropolis Water Act, 1871." N.B. Water is wasted in several ways, as by defective works and arrangements, by improper fittings, and by abuse and neglect ; proper fittings and sound workmanship will give good works a fair commence- ment, but subsequent inspection and repairs will be necessary so long as they are in use. It will be found by experience that it is cheaper to supervise and repair the mains and fittings, rather than to allow water to flow to waste. CHAPTEE XXII THE LAW RELATING TO WATER SUPPLIES IT generally happens that when a water supply is to be pro- vided, land or water rights, or land and way leaves, have to be acquired. This may be done either voluntarily or com- pulsorily, the Public Health Act, 1875, section 175, providing that any Local Authority may purchase, take on lease, sell, or exchange any lands, whether situated within or without their district, and may also buy up any water-mill, dam, or weir which interferes with the proper drainage of, or the supply of water to, their district. It is desirable, if possible, to purchase voluntarily, as the expenses of acquiring land compulsorily are considerable, and add much to the cost, especially in the case of village water supplies. But it frequently happens that the necessary land can only be acquired by compulsory purchase, and to enable Local Authorities to purchase com- pulsorily, the Lands Clauses Consolidation Acts are, by section 176 of the Public Health Act, 1875, incorporated with that Act ; and that section prescribes the course to be taken by a Local Authority before putting in force the powers of the Lands Clauses Acts as to purchasing and taking lands otherwise than by agreement. The Lands Clauses Act, 1845, contains valuable powers, enabling tenants for life and other owners of limited estates to carry out voluntarily sales of the lands in which they are interested. Many persons being incapacitated from selling their lands 382 WATER SUPPLIES by reason of disabilities of various kinds, section 6 of that Act enables all parties entitled to any such lands, or any estate or interest therein, to sell and convey the same, and particularly for all Corporations, tenants in tail or for life, married women seised in their own right or entitled to dower, Guardians, Committees of Lunatics and of Idiots, Trustees or Feoffees in trust for charitable or other purposes, Executors and Administrators, and all parties for the time being entitled to the receipt of the rents and profits of any lands in possession, to sell the same. Similar powers, enabling tenants for life and other persons having less than an absolute interest in lands to sell volun- tarily, are conferred by the Settled Land Act, 1882, under sections 3 and 58 of which a tenant for life, tenant in tail, tenant by the courtesy, and other limited owners, may sell the settled land or any part thereof, or any easement, right, or privilege of any kind for or in relation to the land. There is a prevalent idea that Local Authorities may use roadside wastes for sinking wells and other water-supply pur- poses ; but this is erroneous. Local Authorities, as such, have no rights whatever in these wastes, and the law presumes, until evidence is given to the contrary, that the soil of the roadway to the middle of the road, and of the adjoining strip of waste, belongs to the owner of the land adjoining to the highway or to the strip of waste ; and the owner of the roadway and of the strip of waste is entitled to use his property in every way not inconsistent with the public right of passage, the right of the public merely extending to pass along the surface of the road, and for that purpose to keep it in repair. This presumption as to the ownership of the soil of the roadway has been said to rest on the supposition that when the road was originally set out, the proprietors of the adjoining land each contributed a portion of their land for its formation, and the presumption that the soil of a strip of land lying between the highway and the adjacent enclosure belongs to the owner of that enclosure is founded on the THE LAW RELATING TO WATER SUPPLIES 383 supposition that the proprietor of the adjoining land, at some former period, gave up to the public free passage of the land between his enclosure and the middle of the road, or, when enclosing his land for the road, he left an open space at the side of the road, over which the public might deviate if necessary, to avoid the liability to repair which would other- wise have fallen upon him. If the strip of land communicates with or is contiguous to an open common or large portion of land, the presumption is done away with or considerably narrowed, for the evidence of ownership which applies to the large portions applies also to the narrow strip which com- municates with them. Before proceeding to purchase lands, springs, or streams for water-supply purposes, precautions should be taken (a) To ascertain whether and to what extent neighbouring landowners can prevent, by legal proceedings, the water yielded therefrom being used for the pro- posed water-supply purposes. (b) Whether and to what extent such landowners can, by digging wells, cutting trenches, or executing other works on their own lands, abstract or divert the water proposed to be utilised. As to the first question As a general rule every land- owner (including a Local Authority owning land) has the right to dig wells and execute other works on his land, and thus obtain or divert for his own purposes as much of the water flowing under his land as he can, even though the effect may be to abstract or divert the underground waters which otherwise would flow to and become feeders of springs and streams on other property. But the law is different with regard to a watercourse, which has been defined by Lord Tenterden as "water flowing in a channel between banks more or less defined." The riparian proprietors whose lands adjoin a watercourse may take water from it, but in doing so must have due 384 WATER SUPPLIES regard to the similar rights of others whose lands adjoin the stream, and who have the right " to have the watercourse or stream come to them in its natural state in flow, quality, and quantity." A spring and a stream have been thus defined by Jessel, M.R. "A spring of water is, as I understand it, a natural source of water, of a definite and well-marked extent. A stream of water is water which runs in a defined course, so as to be capable of diversion, and it has been held that the term does not include the percolation of underground water." What is a stream, and where does it begin 1 ? is a question which was raised in the caseof Dudden v. Guardians of the Glutton Union, reported in 11 Exchequer Reports, 627, and 26 Law Journal Reports, Exchequer, 146, where the plaintiff was the owner of an ancient mill which was supplied with water from a brook. Adjoining this brook was a spring, the water from which flowed by a natural channel into the brook. The guardians, for the purpose of supplying the workhouse with water, placed tanks and pipes close to the spring-head, and took the water before it flowed into the natural channel. The judge directed the jury to find for the plaintiff (and they did so) if they thought the water flowed in a defined regular course from the spring-head to the brook. Upon the application to the Court to set aside the verdict, Baron Martin thus stated the law : " The right to flowing water is a natural right, and all parties are entitled to the use of it, but a party would not be entitled to divert it when it is in the act of springing from the ground. He cannot legally prevent its flowing into its natural channel." And Baron Watson added, " If the diversion in this case had taken place ten yards from the spring-head, there would be no doubt in the case, and the rule is the same if the water is diverted at the source." The law respecting the right to water flowing in definite visible channels is clearly enunciated by the judgment of the Court of Exchequer in the case of Embrey v. Owen, reported THE LAW RELATING TO WATER SUPPLIES 385 in 6 Exchequer Reports, 353, and 20 Law Journal Reports, E. 212. This case decided that water is publici juris in this sense only, that all may reasonably use it who have the right of access to it. No man can have any property in the water itself, except in that particular portion which he may choose to abstract from the stream and take into his own possession, and that during the time of his possession only. Also that the proprietor of the adjacent land has the right to the usufruct of the streams that flow through it, not as an ab- solute and exclusive right to the flow of all the water in its natural state, but subject to the similar rights of all proprietors of the banks on each side to a reasonable enjoyment thereof. In the case of Milner v. Gilmour, Lord Kingsdown laid down the law as to running streams as follows : "By the general law applicable to a running stream, every riparian proprietor has a right to what may be called the ordinary use of the water flowing past his land, for instance to the reason- able use of the water for his domestic purposes and for his cattle, and this without regard to the effect which such use may have in case of deficiency upon proprietors lower down the stream ; but further he has a right to the use of it for any purpose, or what may be termed the extraordinary use of it, provided that he does not thereby interfere with the rights of other proprietors either above or below him. Subject to this condition he may dam it for the purposes of a mill, or divert the water for the purpose of irrigation, but he has no right to interrupt the regular flow of the stream if he thereby inter- feres with the lawful use of the water by other proprietors, and inflicts upon them a sensible injury." Such extraordinary use, in order to be justifiable, must, however, be a reasonable one, and one for which a riparian proprietor is entitled to take the water from its natural course ; for where an unreasonable use is made of the water by one riparian proprietor, the. others are entitled to have it restrained, even though they prove no actual damage, on the ground that it is an interference with 2c 386 WATER SUPPLIES a right which, unless restrained, would in the course of twenty years confer on the claimant a right of prescription in dero- gation of the prior right. It would appear from the case of the Swindon Water Co. v. Wilts and Berks Canal (Law Reports, 9 Ch. 457), that an " extraordinary use," as well as being reasonable, must be for the use of the riparian tenement. But the law as laid down in these cases is inapplicable to the case of subterranean w r ater not flowing in any separate channel, or flowing indeed at all in the ordinary sense, but percolating or oozing through the soil, more or less according to the quantity of rain that may chance to fall. The case of Broadbent v. Ramsbotham, reported in 11 Exchequer Reports, 611, and 26 Law Journal Reports, Ex. 115, decided that the right of a riparian owner to the lateral tributaries or feeders of the main stream applies to waters flowing in a defined and natural channel or watercourse, and does not extend to water flowing over, or soaking through, previous to its arrival at such watercourse. In this case it was decided that the plaintiff", who was a millowner, having the right to use the water of a natural stream, called Longwood Brook, had no cause of action against the owners of adjacent land for diverting water, which, coming from a pond formed by landslips, escaped over the surface of this land, and thence, by natural force of gravity, found its way by land-drains or dykes to the brook ; or for diverting the overflow from a well and a swamp on that land, which ran in wet seasons to the brook ; or for diverting the overflow from another well on that land used as a watering-place for cattle, which overflow formed a stream, and, after following the course of an artificial ditch, along a hedge-side, and in other parts flowing down a small channel, formed by the water, and over swampy places, where the cattle had trodden in the soil, ran over a field, and thence along a natural valley, and along hedge -sides and ditches, and discharged itself into the brook ; and it was held that the plaintiff, although he had a right to the use of the water of the THE LAW RELATING TO WATER SUPPLIES 387 brook, had no cause of action against the owner of the adjacent land for diverting either of the above three sources of supply before the waters had arrived at a definite natural watercourse. With regard to the second question, the law has been defined and settled by two important decisions of the House of Lords, the first of Chasemore v. Richards, decided in July 1859, and reported in 7 House of Lords Reports, 382, and 29 Law Journal Reports, Exchequer, 81, which decided that the owner of land, containing underground water which percolates by undefined channels, and flows to the land of a neighbour, has the right to divert or appropriate the percolating water within his own land, so as to deprive his neighbour of it. In that case, much of the law relating to waters flowing above or underground was dealt with by the various learned judges who delivered judgments. The facts of the case and the law relating to it were stated by Mr. Justice Wight- man as follows : "The plaintiff is an occupier of an ancient mill on the river Wandle, and for more than sixty years he and his predecessors had used and enjoyed, as of right, the flow of the river for the purposes of working their mill; the river had always been supplied above the plaintiff's mill, in part, by the water produced by the rainfall on a district of many thousand acres in extent, comprising the town of Croydon and its vicinity. The water of the rainfall sinks into the ground to various depths, and then flows and per- colates through the strata to the river Wandle, part rising to the surface, and part finding its way underground in courses which continually vary. " The Croydon Local Board sink a well in their own land in the town of Croydon, and by means of the well and by pumping from it large quantities of water for the supply of the town of Croydon, the Board abstracted and interrupted underground water (but underground water only) that other- wise would have flowed and found its way into the river Wandle, and so to the plaintiffs mill, and the quantity so 388 WATER SUPPLIES diverted was sufficient to be of sensible value toward working the mill." The law as decided in Chasemore v. Richards has- been followed and extended by the important recent case, decided by the House of Lords in July 1895, of the Mayor, Aldermen, and Burgesses of the Borough of Bradford v. Edward Pickles, where it was decided that not only has the owner of land containing underground water which percolates by undefined channels and flows to the land of his neighbour the right to divert or appropriate the percolating water within his own land so as to deprive his neighbour of it, but his right to do this is the same whatever his motive may be, whether to improve his own land or maliciously to injure his neighbour or to induce his neighbour to buy him out. In this case the Corporation of Bradford were the owners of Trooper Farm and certain springs and streams rising in or flowing through that farm, which were purchased many years ago by the Bradford Waterworks Company, and from which the Cor- poration obtained a valuable supply of water for the domestic use of the inhabitants of Bradford. In 1892 the respondent Pickles began to sink a shaft on his land adjoining Trooper Farm, and also to drive a level through his land for the professed purpose of draining the strata with the view to the working of his minerals. These operations had the effect of diminishing the water supply obtainable from the springs on Trooper Farm. The Corporation of Bradford brought this action to restrain the defendant Pickles from continuing to sink the shaft or drive the level, and from doing anything whereby the waters of the spring and the stream might be drained off or diminished in quantity. Lord Halsbury, in delivering judgment, said : " The acts done or said to be done by the defendant were all done upon his own land, and the interference, whatever it is, with the flow of water, is an interference with water which is underground and not shown to be water flowing in any defined stream, but is percolating water which, but for such interference, THE LAW RELATING TO WATER SUPPLIES 389 would undoubtedly reach the plaintiffs waterworks, and in that sense it has deprived them of the water which they would otherwise get ; but although it has deprived them of water which they would otherwise get, it is necessary for the plaintiffs to establish that they have a right to the flow of water, and that the defendant has no right to do what he is doing. I am of opinion that the question whether the plaintiffs have a right to the flow of such water is covered by the decision in the case of Chasmore v. Richards. The very question was then determined by this House, and it was held that the landowner had a right to do what he had done, whatever his object or purpose might be, and although the purpose might be wholly unconnected with the enjoyment of his own estate." In delivering his judgment, Lord Macnaughten stated : " The position of the appellants is one which it is not easy to understand. They cannot dispute the law laid down by this House in Chasemore v. Richards. They do not suggest that the underground water with which Mr. Pickles proposes to deal flows, in any defined channel. But they say that Mr. Pickles' action in the matter is malicious, and that, because his motive is a bad one, he is not at liberty to do a thing which every landowner may do with impunity if his motives are good. It may be taken that his real object was to show that he was the master of the situation, and to force the Corporation to buy him out at a price satisfactory to himself. Well, he has something to sell, or, at any rate, he has something which he can prevent other people enjoying without paying for it. Why should he, he may think, without fee or reward, keep his land as a storeroom for a commodity which the Corporation dispense, probably not gratuitously, to the inhabitants of Bradford. He prefers his own interests to the public good. He may be churlish, selfish, and grasping. But where is the impulse. Mr. Pickles has no spite against the people of Bradford. He bears no ill-will to the Corporation. They are welcome to 390 WATER SUPI'LIES the water, and to his land too, if they will pay the price for it. So much, perhaps, might be said in defence, or in palliation of Mr. Pickles' conduct, but the real answer to the claim of the Corporation is that in such a case motives are immaterial. It is the act, not the motive for the act, that must be regarded. If the act, apart from the motive, gives rise merely to damage without legal injury, the motive, however reprehensible it may be, will not apply without element." The law as to the making and recovery of water-rates and water-rents is much in need of consolidation and amendment. The Waterworks Clauses Act, 1863, and certain provisions of the Waterworks Clauses Act, 1847, are incorporated with the Public Health Act, 1875, and the following clauses of the 1847 Act may be referred to, as to water-rates and water-rents : "Sees. 48 to 52. Any owner or occupier of a dwelling- house may open ground, and lay communication or service pipes to connect house with mains. "Sec. 53. Every owner and occupier, when he has laid such communication pipes and paid the water-rate, is entitled to a sufficient supply of water for domestic purposes. " Sec. 68. Water-rates (except as in sec. 72) are to be paid by the person receiving or using the supply of water, and to be payable according to the annual value of the tenement supplied, any dispute arising as to such value to be settled by two justices. " Sec. 69. When several houses, or parts of houses in the separate occupations of several persons, are supplied by one common pipe, the several owners or occupiers are liable to the payment of the same water-rates as if each were supplied by a separate pipe. "Sec. 70. Water-rates to be paid in advance, by equal quarterly payments, at Christmas Day, Lady Day, Midsummer Day, and Michaelmas Day. " Sec. 72. The owners of all dwelling-houses or separate THE LAW RELATING TO WATER SUPPLIES 391 tenements, the annual value of which does not exceed ..10, are liable to payment of the water-rates instead of the occupiers." To make the owner or occupier liable, it is not necessary that the water should be laid on to the house, section 9 of the Public Health Water Act, 1878, enacting that where a stand pipe has been provided water-rates or water-rents may be re- covered from the owner or occupier of every dwelling-house within 200 feet of any such stand pipe, in the same manner as if the supply had been given on the premises. But if such dwelling-house has within a reasonable distance, and from other sources, a supply of wholesome water sufficient for the consumption and use of the inmates, no water-rate or water-rent is recoverable from the owner or occupier until the water supplied from the stand pipes is used by the inmates of the house. This section applies to rural districts only. Where stand pipes are used questions are often raised by householders, who seem to object to water-rates, even more than to other rates, on the ground that their houses are pro- vided with water from some ancient well, or other source. A little patience is generally not wasted on them, for if left alone they soon find using the water from the stand pipe to be so great a convenience that they take to using it, and then pay the water-rates with as good grace as they do other rates. In some cases, however, where a water-rate hater insists on continuing to use water from some polluted well or other source, it becomes necessary to compel him to pay the water- rate, even though he does not use the water from the stand pipe, on the ground that his supply is not wholesome. When compelled to pay the rate he will soon begin to use the water, to get over his objection to being made to pay for what he does not use. " Sec. 74. If a person liable to pay water-rates neglects to do so, water may be cut off, and water-rates and expenses of cutting off the water recovered in manner mentioned in the section." 392 WATER SUPPLIES Objection is often made that the incidence of a water-rate is unfair, because, assuming the water-rate to be Is. in the y an Oil Engine. At a recent gathering of Medical Officers of Health, Dr. Ashby of Reading gave a very interesting account of the waterworks recently established for the supply to a village (Sonning) in his district. He stated that the water was derived from a boring in the upper chalk, 75 feet deep, yielding about 70 gallons per minute. The reservoir has a capacity of 35,000 gallons, and the rising main from the well to the reservoir is 4 inches diameter and 1783 feet in length. The main enters the top of the reservoir at about 100 feet above the level of the water in the bore-hole. The reservoir is about 4000 feet from the commencement of Sonning village, its bottom being about 48 feet above the highest, and 83 feet RURAL AND VILLAGE WATER SUPPLIES 413 above the lowest parts of the village. The distributing mains consist of 4390 feet of 4-inch pipe and 3935 feet of 3-inch pipe. There are sixteen hydrants, five air-valves, and seven sluice-valves, besides one on the draw-off pipe at the reservoir. The engine-house cost 124, the engine and pumps 260, the tube well 73, making a total of about 457 for the entire pumping station and well. The total cost of the works was 1840. With the sanction of the Local Government Board 1800 was borrowed; of that sum 400 has to be repaid in fifteen years and 1400 in thirty years. To repay the annual instalments of principal and interest, and to cover the cost of pumping and other expenses, a rate of Is. in the pound on houses and 3d. on land is required, besides the water rate charged on the occupiers of premises actually supplied. The charges for domestic supplies are 7s. a year for all houses under 14 rateable value, and 2J per cent on the rateable value of all other houses, and some extra charges for farmyards, cowkeeping, and livery stables. The expense is considerable, but, as Dr. Ashby remarks, " it would have cost but little more to have supplied a considerably larger place." Sonning has a population of 515 persons, and its rateable value is 4398. The oil engine is of two brake horse-power, and the pumps are a set of treble ram pumps, with gun metal plungers 4 inches in diameter by 9 inches stroke. They are fixed to the suction pipe at the top of the lining tube of the bore-hole. Dr. Ashby made a very careful series of observations, showing the capacity of the pumps and the cost of pumping. He says : "From 3rd September to 30th September 1894, we pumped 31 \ hours on 11 days. During the whole of that time I was present and took exact observations of all the materials which were consumed. We could have done the pumping in four days, but we pump more frequently in order to keep a good stock of water in the reservoir in case of any fire occurring, or in the event of the machinery requiring any repairs, so that the village may not be without water. We 414 WATER SUPPLIES consequently use rather more oil in starting the engine than would be absolutely necessary. In that time the pumps made 57,397 revolutions, an average of 1822-1 an hour. There are 7 '2 revolutions of the engine to 1 revolution of the pumps, so the engine ran at an average speed of 218*65 revolutions per minute. The total quantity of water raised was 75,764 gallons, or an average of 2 40 5 "2 per hour. The supply per head of the population per day was about 7 gallons. " The consumption of materials was as under : s. d. 12 gallons of tea rose oil ... at 5d. 5 1 battery charge . . . . at Is. 1 1| zinc for battery . . . . at 3d. 4^ 24 fluid ounces of sulphuric acid . at 2d. per Ib. 5A Total cost of material consumed by the engine . . 610 3^ pints of lubricating oil for engine and pumps at 2s. a gall. 1( Cotton waste . . . . at 4d. per Ib. 3 Total cost of materials consumed by engine and pumps . 8 Cost of materials for engine per 1000 gallons of water raised 100 feet high 1*082 penny Total cost of materials for engine and pumps per 1000 gallons of water raised 100 feet high 1 '267 penny Consumption of oil per h.p. per hour . . l - 5 pint." Spring Water pumped by Gas Engine. Great Baddow and Springfield are two adjoining villages with a population of about 4000. The waterworks are situated in a piece of ground near the spring. The spring yields 120,000 gallons per day. For the past fifteen years one eight horse-power gas (Crossley Otto) engine and set of pumps have been sufficient to raise all the water required ; but this year a new eight horse-power (Crossley Otto) with a set of three- throw pumps has been erected as a duplicate. There are four reservoirs 24'xl2'x6' brick-built and covered with brick arches, each holding 10,350 gallons. RURAL AND VILLAGE WATER SUPPLIES 415 The water is pumped twice daily from these reservoirs to a tank holding 40,000 gallons on the top of a tower 96 feet high. The villages are then supplied by gravitation. One engine will work both sets of pumps at once, raising 20,000 gallons per hour. The amount of gas used in pumping is 200 feet per hour for the new engine and 250 feet per hour for the old engine. Gas at 3s. 4d. per 1000 feet. The total expense for working is about 180 per year. The amount of water rents collected from the houses supplied is about <350 per annum. Where water is supplied by metre the charge is Is. per 1000 gallons. O g ^ <3 it fl o o 2 boa 2^3 so i^i c 01-s^-tl Mia 5 i 2 .2 i-H rH O rH i-H Oi O O O I-l T-H 3S M ._ - r*-t H 5 rH r-H O PnPn -fl t>0 3 ^ fl t^' ^3 'S'S ^ 6 Qflfl a Q J 2E APPENDIX 1. CRENOTHRIX, CAUSE OF DISAGREEABLE ODOURS IN WATER. CKENOTHRIX, a fungoid growth of thread-like form, can only thrive in water containing protoxide of iron and organic matter, and, by its decomposition, often causes water to acquire a disagreeable odour and taste. The Berlin water supply from wells sunk near the Tegeler Lake had to be abandoned on account of the abundant growth of this organism. Its appearance in the Rotterdam water supply led to the formation of the "Rotterdam Crenothrix Commission," and Prof. Hugo de Vries reported that Crenothrix was not a ground water organism as was generally supposed, but that it was found in many surface waters. As the result of his observations and experiments, he expressed the opinion that two factors are necessary for its growth to become so rapid as to render a water unpalatable. These two factors are the presence of decomposing organic matter, and the presence of protosalts of iron. For a detailed account of this organism and its relation to water supplies, an exhaustive article by Prof. "W. F. Sedgwick, in the Technological Quarterly, Boston, 1890, may be consulted. In the Annual Report of the Massachusetts State Board of Health, there is also a mass of information bearing upon this subject ; and in Public Health for October 1896, Dr. Garrett describes the effect of this organism on the Cheltenham water supply. 2. EFFECT UPON HEALTH OF ZINC- CONTAMINATED WATER. Zinc poisoning from the use of water which has been stored in galvanised iron receptacles is of comparatively rare occurrence. Obstinate constipation is, so far as experience extends, the one notice- able effect produced, and possibly zinc-contaminated water may be a more frequent cause of this condition than has hitherto been suspected, but Myelius states that the water of the parish well at Tutendorf contains half a grain of zinc per gallon, and has been used for about a century without any perceptible effect. APPENDIX 419 3. PLUMBO-SOLVENT ACTION OF MOORLAND WATER. In 1890 the Medical Department of the Local Government Board was entrusted with an investigation respecting the causes of the lead poisoning which has been referred to public water supplies derived from moorland sources. This investigation has been undertaken by Mr. W. H. Power, F.R.S., and an interim report has just been pre- sented, based upon data collected for the West Riding of Yorkshire by Dr. Barry, and for Lancashire, Cumberland, and Westmoreland by Mr. T. W. Thompson. With reference to this subject, Dr. Thorne, in his last Report to the Local Government Board, says " Observations were, in the first instance, confined to the gathering ground at Burnmoor, near Settle, in Yorks, water from different parts of which were, for some eighteen months, examined week by week as to their physical, chemical, and bacteriological features, the results being recorded along with concurrent meteorological and other condi- tions, and compared with the ability of the same water week by week to take lead into solution. With the latter only one chemical condi- tion has been found generally parallel, while none of the other condi- tions observed have been at all parallel. This is the amount of acidity of the water. And a similar correspondence was found to exist when the experience of Burnmoor was applied to other gathering grounds. For although the amount of lead taken up by one water as compared with another was not always found to be in direct proportion to the relative acidities of the two, yet, for a particular water, variations in its lead-dissolving property were always associated with corresponding variations in the amount of its acid. " The problems of plumbo-solvency of a moorland water thus came to be, in large measure, problems of the particular acidity connected with it, and accordingly experiments were undertaken to determine the nature of this acidity and its source. Having ascertained that a moorland water has not in itself any power of developing or increasing in acidity, it remained to be discovered where in its moorland history the water acquired its acid properties. It was soon ascertained that it was from the peat that the water derived this quality ; and the question next arose whether the acidity of the water was due to merely chemical and physical reaction of the water and the peat or to active organic life in the peat itself. The answer is indicated in the experi- ments so far reported on. They show that while neither moorland water nor a sterile decoction of peat can of itself develop acidity, the addition to either of a minimal amount of moist peat soil will cause bacterial growth in it, with increasing development of acid reaction and ability to dissolve lead. 420 WATER SUPPLIES "And they have further indicated two species of microbes which, alone among the many kinds of micro-organisms found in the samples of peat examined, have the power of producing acidity when added to a sterile decoction of peat. "At this stage, then, Mr. Power's forecast of 1887 would seem to be borne out as the result of the labours of the experts who have been engaged in this inquiry. The investigation is, however, by no means completed, and it is being continued throughout the current year." Dr. Scatterby (Public Health, May 1895) describes the filtering arrangements made to neutralise the plumbo-solvent action of the peaty water supplied to Keighley. He says : ' ' These works, completed at a cost of 18,000, consist of three beds of Welsh coke (to extract the grosser peat} 7 impurities), four sandstone and limestone niters, four polarite chambers, and a clean water reservoir." By this filtration the acid so invariably found in moorland water supplies is neutralised by the limestone of the filters, and by this means it is hoped to completely destroy the solvent action of the water on the lead piping. 4. POLLUTION OF WATER IN RESERVOIR. OUTBREAK OF TYPHOID FEVER. During the latter half of 1893 an epidemic of typhoid fever occurred in and around Paisley, affecting over 800 people. Dr. Munro, the County Medical Officer, attributes it to the pollution of the water supply, and upon visiting the reservoir a month after the beginning of the epidemic he found that until the 6th of July there had existed close to the margin of the water an inhabited farm house, "the drainage or soakage from which could only escape into the reservoir." Dr. P. Frankland, who examined the collecting ground and the filter beds, proved that the filters were in an unsatisfactory state. 5. POLLUTION OF WATER SUPPLY BY MELTING SNOW. OUTBREAK OF TYPHOID FEVER. In 1885 an outbreak of typhoid fever occurred in Pennsylvania. 1200 people were attacked and 150 died. Stampfel states that during the early spring the dejecta from a typhoid patient was thrown upon the snow lying on a hill sloping towards the source of the public water supply. A sudden thaw setting in, the impurities would be carried down with the melted snow. This occurred on 25th March, and on 10th April the epidemic commenced. Just at that time the water from this particular source was being used to an unusual extent. Those who derived water from other sources were not affected. APPENDIX 421 6. POLLUTION OF WATER IN MAINS. Mr. M. A. Adams, 'F.R.C.S., Medical Officer of Health for the borough of Maidstone, in his Annual Report for 1894 (quoted in Public Health, July 1895) states that he found in May that the water from a particular hydrant was polluted. Upon investigating the cause, the main was found to be defective at two points near a disused drain. Mr. Adams explains the insuction of foul matters by stating that there^was a tendency for this service pipe to empty itself in favour of the lower placed hydrants, and when the taps at these lower places were shut off, a wave of water pressure was sent forward to the higher level ; when this wave reached the hydrant implicated, the water recoiled upon itself, and set up a sudden and strong retreating .current in the opposite direction, which produced the insuction. He adds, "This seemingly small matter ought not to be lost sight of ; it teaches a practical lesson in hydraulics of the greatest sanitary importance." 7. POLLUTION OF A DEEP WELL NEAR EDINBURGH. In the Edinburgh Medical Journal for November 1894, Dr. A. C. Houston gives an account of a well at Morningside, 294 feet deep, which yielded polluted water. The pollution was apparently due to the discharge of sewage into a quarry 800 feet away, since the pollution ceased soon after the sewage was diverted into the Edinburgh sewers. 8. TYPHOID FEVER IN THE BOLAN PASS. Surgeon - Captain Haynes states that in the Bolan Pass in 1877 typhoid fever was caused by drinking a few ounces of water from a well in which a dead camel was found, yet that the natives who had been drinking the water some time did not contract the disease. He also remarks that native troops can live in barracks which have had to be vacated by our men on account of the prevalence of typhoid fever and cholera. 9. SELF-PURIFICATION OF STREAMS. The effect of the sun's rays upon the organisms found in water has been studied by many observers. Dr. Procacci exposed water in deep cylinders to the nearly vertical rays of the sun, and found that all the organisms in the water up to a certain depth were killed. After three hours' exposure the water in the cylinders to 1 foot depth was nearly sterile, whilst at a depth of 2 feet they were unaffected. Prof. Buchner exposed gelatine plates sown with typhoid bacilli in water at various 422 WATER SUPPLIES depths for a period of four and a half hours, and found that all those plates covered with less than 5 feet of water, were sterilised. Those exposed at a depth of 10 feet were not affected. Percy Frankland has proved that in the Thames and Lea there are often twenty times more organisms present in the water in winter than in summer, but this he thinks may in part be due to the greater proportion of spring water contained in the streams in summer, since spring water contains comparatively few organisms. When a little common salt is added to water the sterilising effect of the sun's rays is said to be increased. With reference to the great variation in the number of bacteria in river water during the course of the year, Prof. E. Frankland, in his Report on Metropolitan Water Supply, 1894, says, "that the number of microbes in Thames water is determined mainly by the rate of the flow of the river, or, in other words, by the rainfall, and but slightly, if at all, by either the presence or absence of sunshine, or a high or low temperature." Dr. D. Harvey Attfield (Brit. Med. Journ., 17th June 1893) describes the results of a series of experiments undertaken by him -in Munich to ascertain the effect of Infusoria upon the bacteria in polluted water. He concludes that "Infusoria would seem to have some powerful influence in the getting rid of bacteria, and, possibly, so aiding in the ' self- purification' of water." GENEEAL INDEX ABYSSINIAN tube wells, 310 yield of, 312, 313 cost of, 314 Action of frost on water mains, 375 of water on metals, 8 Advantages of softened water, 120 Alum, clarification by, 255 Amount of water required for domes- tic and other purposes, 272 used, constant supply, 274 by cattle, 283 intermittent supply, 274 in tropical climates, 282 available from various sources, 285 Analyses, vide Tables the interpretation of, 160 ammonia, 169 chlorine, 161 nitrates, 164 nitrites, 165 organic ammonia, 172 organic carbon and nitrogen, 171 oxygen absorbed, 173 phosphates, 170 Animal charcoal, properties of, 253 Animals, effect of polluted water upon, 157 Aqueducts, fall of, 370 Artesian wells, 70, 320 Aster ionella, 108 BACTERIA in water, 113, 185 effect of sunlight upon, 223, 421 sedimentation upon, 220 Bacteriological examination of water, 185 Ball hydrants, dangers of, 212 Beggiatoa alba, 110 Blasting of deep wells, 325 Bogs, marshes, and swamps, 41 Boiling point of water, 5 Bore-tube, advantages and disadvan- tages of pumping from, 316 varieties of, 319 Brine, yielded by well, 302 Bursaria gastris, 108 CARBONIC acid in water, 6 Cast-iron mains, 372 acted upon by soft water, 206 Catchment basins, 86, 295 Chalk, water held by, 44, 74, 301 Ghara fcetida, 109 Charcoal, animal properties of, 253 vegetable properties of, 253 Chlorine in surface waters, 31 signification of, 161 Cholera, 148 and improved water supplies, 150 and defective filters, 153 and water filtration, 190 organisms, influence of soil on, 309 outbreaks of, Altona, 151, 187 232 Hamburg, 151, 187 London, 148 Poonah Jail, 151 They don Bois, 150 Vadakencoulam, 151 Wandsbeck, 151 Cisterns, action of water on, 205 house, 204, 369 rain-water, 21 424 WATER SUPPLIES Clarification of water by alum, 255 Classification of potable waters, 11, 27 Collection of rain water, 25 Colour of water, 2, 105 removal by filtration, 235 Communication pipes, 371 Composition of water, 1 Conduits, open, 370 Conferva Bombycina, 109 Constant supply, 274, 369 Constituents of natural water, 7, 115 Construction of wells, 305 Consumption of water, daily varia- tion in, 283 hourly variation in, 277, 364 Cost of public water supplies, 35, 37, 82 boring wells, 321 tube wells, 314 well sinking, 314 Cottage filter, 252 Crenothrix, 108, 364, 418 Cryptomonas, 108 DAIRY farms, 383 Dead ends, 373 Deep-well water, 27, 70, 80 wells, boring of, 319 cost of, 320 effect of pumping on, 78 increased supply by blasting, 325 pollution of, 75, 203, 421 site, selection of, 77 yield of, 80, 83, 303, 326 Density of water, 4 Depth of mains, 372 Deserts, 15 Diarrhoea, 122 due to distilled water, 254 decomposing animals in water, 125 sewage in water, 124 sewer gas in water, 123 sulphuretted water, 123 turbid river water, 123, 124 Diseases due to animal parasites, 154 specific organisms, 130 Distillation of water, 12, 254, 257 sea water, 254 Distributing mains, 371 Distribution of water, 369 Divining rod, 290 Domestic consumption of water, 277 filters, 247 dangers of, 251 high pressure, 247 low-pressure, 247 limited utility of, 251 self-supplying, 250 Domestic purification of water, 247 Drainage area, 295 Drinking water, qualities of, 104 Dual supply, 303 Duties of Sanitary Authority to supply water, 395 Dysentery, outbreaks due to impure water 125. 184 EARTH, living, action of, 47 Eels in water mains, 111 Electricity, decomposition of water by, i Engines, pumping gas, 353 oil, 352 steam, 353 water, 344 wind, 341 Enteric fever vide Typhoid fever Entozoa, affecting man, 155 Evaporation, loss of water by, 297 rate of, 12 from the ocean, 12 Expansion of water when freezing, 3 FACTORS influencing amount of water available, 91 Ferrule machine, 373 Filter beds, 236, 242 area of, 237 area of, to calculate, 238 cleansing of, 236, 239 construction of, 235, 245 effect of scraping, 230 polarite, 242, 253 Filters, cottage, 252 domestic, 247 high pressure, 247 low pressure, 247 limited utility of, 251 self-supplying, 250 Filtration and cholera, 190 GENERAL INDEX 425 Filtration at Altona, 232 by machinery, 240 nitrification during, 234 rapidity, 232 removal of colour by, 235 efficiency of, 227, 233 Finding, water, 290 Fire extinction, water reserve for, 365 Flow of water through mains, 371 Formulae, Pole's, for yield of catch- ment area, 297 storage, 299 Eytelwein's, for velocity, 370 Burton's, for fire reserve, 365 Freezing point of water, 3 Friction, loss of head by, 371 Frost, action on mains, 375 GALVANISED iron cisterns, 205 pipes, 257 Gauging of springs and streams, 95, 287 wells, 292 Goitre, 126 alleged causes of, 127 localities in which prevalent, 126 Granite, water held by, 44 Gravel, pocket of, 41 Gravitation works, 360 Ground water vide Subsoil water HARD water, 7 cost of softeuiiiff, 257, 261, 266, 268 influence on health, 117 softening processes, 256 waste caused by, 119 Hazel twig, effect of water upon, 290 Head of water, 239 loss by friction, 371 Health, effect of impure water upon, 122 " Health " pipe, 130, 374 Heat, effect on water, 214 latent, of water, 3 Horse-power, definition, 354 equivalent in water raised, 355 Hourly variation in supply, 277 consumption, inequality of, 364 House cisterns, 204, 369 Hydrants, ball, dangers of, 212 Hydraulic rams, 344 efficiency of, 346 IMBIBITION, 42 Impervious strata, 41 Impounding reservoirs, 257, 358 Impure water, effect upon animals, 157 e fleet upon health, 122 Incompressibility of water, 2 Inequality of hourly consumption, 364 Influence of soil on cholera and typhoid organisms, 309 Insuctiou at water joints, 210 Interlacing system of mains, 373 Intermittent pollution, 174, 192 supply, dangers, 211 to various towns, 274, 369 Interpretation of water analyses, 160 Iron in water, 8, 10 Is water analysis a failure ? 175 Isolated houses, supply for, 285 JOINTS of water mains, 372 fouling by hemp stuffing, 372 Joints, insuction at, 211 LAKES, 33 as reservoirs, 33, 35 Laws relating to water supplies, 381 Lands Clauses Consolidation Acts, 381 Limited Owners Reservoir, etc., Act, 396 Public Health Act, 381, 390, 392, 394 Public Health (Scotland) Act, 399 Public Health (Water) Act, 381, 391, 394, 401 Settled Land Act, 382 Waterworks Clauses Acts, 390, 392 Cases- Borough of Bradford v. Pickles 388 Broadbent v. Ramsbottom, 386 Chasemore v. Richards, 387 Dudden v. Guardians, Glutton Union, 384 426 WATER SUPPLIES Cases Embrey v. Owen, 384 Holmfirth Local Board v. Shore, 397 Milner v. Gilmour, 385 Smith v. Archibald, 399 Swindon Water Co. v. Wilts and Berks Canal, 386 Wandsworth Board of Works v. United Telephone Co., 399 Lead cisterns, 205, 206 pipes, 109, 208 in water, 8, 21, 129 Lead poisoning, 8, 128 symptoms of, 128, 209 Legal decisions affecting water sup- plies, 384 Limestone, water held by, 44, 74 Limited Owners Keservoirs and Water Supply Further Facilities Act, 396 Living earth, action of, 47 Loss of watep by evaporation, 297 percolation, 297 Lyngbya muralis, 110 MAGNESIA, sulphate of, 302 Magnetic carbide, 244 Mains, cast-iron, 372 dead ends, 373 depth of, 372, 374 diameter of, 370 distributing, 371 eels in, 111 flow of water through, 371 house service, 371, 374 insuction of filth by, 211 interlacing system of, 373 joints of, 372 trunk, 371 velocity of water in, 370 Malaria, 131 decrease in England, 131 outbreak on board ship, 132 where prevalent, 132 Maximum consumption of water, 365 density of water, 4 rainfall, 92 Mean consumption of water, 365 Metallic impurities in water, 8, 10, 128, 210 Metropolitan Water Supply, Royal Commission report on, 72, 88 89, 94, 191, 238, 277 Mineral waters, classification of, 11 Minimum rainfall, 92 Moisture in atmosphere, 13 Moorland waters, 27 Movements of subsoil water, 44, 200 NATURAL water, constituents of, 7 classification of, 11, 27 Nitrates and nitrites, how formed, 196 in chalk waters, 166 reduction of, 168 signification of, 164 Nitrification during filtration, 234 process of, 196 Nitrogen, organic, 171 Nitrogenous organic matter, 171 Nostoc, 109 ODOUR of water, 2, 106 caused by Ast&rionella, 108 Begyiatoa alba, 110 Bursaria gastris, 108 Charafoetida, 102, 109 Conferva Bombycina, 109 Crenothrix, 108, 364, 418 Qryptomonas, 108 Lyngbya muralis, 110 Nostoc, 109 Oscillatorice, 110 Spongilla flumatilis* 108 Tabellaria, 108 Uroglena Americana, 107, 108 hemp joints, 207 tar varnish, 372 due to dead animals, 111 sulphuretted hydrogen, 106 Odours of water, classification of 107 Oolite, water held by, 44, 74, 302 Organic matter in water, 170 Organisms in water, 113 bacteria, 113, 185 higher fungi, 114 low forms of animal and vegetable life, 115 Oriental boils, 154 Osdttatoricc, 110 Oxidation in running water, 217 GENERAL INDEX 427 Oxidising effects produced by sand filtration, 236 Oxygen in water, 6, 217, 219 absorbed by water, 173 PALATABILITY of water, 111 Parasitic diseases, 154 Parish Councils and water supplies, 393, 396 Peaty water, 29 effect of storage on, 363 Pebble beds, water held by, 44 Percolation, 43, 45 loss by, 297 Permeability of subsoil, 43 Pervious strata, 41 Phosphates in water, 170 Plumbo-solvent action of water, 8, 10, 419 how prevented, 10, 209, 420 Pockets of gravel, 41 Polarite filter beds, 242, 244, 253 Polluted water, effect on health, 122 effect on animals, 157 Pollution of rain water, 21, 194 rivers, 87, 194 subsoil water, 48, 196 surface water, 194 deep- well water, 75, 203, 421 Pollution of water at its source, 194, 420 during storage, 203, 213, 420 distribution, 206, 211 Pollution by suspended mineral matters, 123 sulphuretted hydrogen, 123 sewer gas, 123 sewage, 124, 125, 133, 134 surface water, 125 Pollution, sources of, action of water on pipes, 206 cisterns and tanks, 204 burial of carcases, 202 cattle, 201 cesspools and house drainage, 194, 199, 201 coal gas, 202 cultivated land, 194 exposure to dust, 213 farmyards, 137, 194, 198 graveyards, 202 Pollution, insuction through ball- hydrants, 211, 421 defective mains, 136, 213 stool taps, 136, 211 sewage, 195 sewer gas, 6, 123 snow, melted, 420 sulphuretted hydrogen, 123 tar varnish, 372 tow joints, 207 washings from roof, 194 Pollution, special methods of tracing, 137, 184 of rivers, Royal Commission on, 27, 40, 67, 69, 74, 88, 117, 149, 164, 166, 169, 171-207, 209, 256, 274, 282 Ponds, 32 Potable water, definition of, 121 classification of, 11, 27 Previous sewage contamination, 166 Public Health Act, 381, 390, 392, 394, 397 Public Health Water Act, 381, 391, 394, 401 water supplies, description of, 404 Pumping from bore tube, 316 mains, velocity of water in, 370 Pumps and pumping machinery, 332, 339 amount of water raised by, 337 efficiency of, 338 varieties of, 332 Purchase of land and water rights, 381 Pure water, definition of, 2 Purification of water by sedimenta- tion, 225, 227 filtration, 228 fermentation, 255 softening process, 271 alum, 255 permanganate of potash, 255 flow of river, 215 nitrification, 48, 196, 234 Purification of water, domestic, 247 Koch's remarks on, 231 Massachusetts, experiments on, 228 Purposes for which water is required, 273 428 WATER SUPPLIES QUALITY of drinking water, 104 Quantity of water obtainable from different sources, 295 required for domestic and other purposes, 272 supplied in different towns, 276 used in towns with constant supply, 274 intermittent supply, 274 tropical climates, 282 by cattle, 283 RAIN, causes of, 13 Rain-bearing winds, 14, 15 Rainfall, 14, 15, 34, 92 at equator, 15 Kew, Greenwich, Massachu- setts, 16 available supply of water from, 26, 294 collected by rivers, 92 how estimated, 16 in gallons per acre, 19 Rain-gaTige, 16 position, 17 mountain, 18 Rain water, 12, 19 action on lead, 21 cisterns, 21 collection of, 25 filtration of, 25 how polluted, 21 impurities in, 20 separator, 23 storage of, 21, 26, 367 Ram, hydraulic, 344, 346 Regulations under Metropolis Act, 375 Reserve for fire extinction, 365 Reservoirs, 33, 366 impounding, 357 natural, 362 service, 359, 362 settling, 359 River water, 27, 86 revolving purifier, 242 suitability of, for public supplies, 90, 220 towns supplied by, 101 Rivers and watercourses, amount of water available from, 92 origin of, 86 Rivers and watercourses, laws relat- ing to, 383, 384 percentage of rainfall collected in, 93 pollution of, 87 pollution. Royal Commission on, 27, 40, 67, 69, 74, 88, 117, 149, 164, 166, 169, 171, 207, 209, 256, 274, 282 self- purification of, 88, 215 subterranean, 46 velocity of flow, 95 Roofs, water collected from, 25 Rural water supplies, 400 law relating to, 381 SAND, water held by, 44 filtration, experiments on, 228 requisites for efficiency, 231, 233, 239 washing, 236, 246 Sandstone, water held by, 44, 74, 301 Saturation of rock, 42 Scrubbers, 240 Sea water, distillation of, 254 for sewer flushing, 104 Search for water, 289 Selection of source of supply, 284 Self -purification of rivers, 88, 215, 421 effect of bacteria, 223 infusoria, 422 oxidation, 219 sedimentation, 220 sunlight, 223, 421 Separator, rain-water, 23 Service pipes, 374, 376 unsuitable, 285 reservoirs, 359 Settling reservoirs, 359 Shallow wells, 46 pollution of, 198 Slime on filter beds, action of, 231 Soft water, 7 advantages and disadvantages of, 120 Softening of water, 256 by addition of lime, 257 Archbutt and Deeley's process 263 Atkins' process, 259 GENERAL INDEX 429 Softening of water, by boiling, 256 distillation, 257 Gitteus' process, 263 Howatson's process, 263 Maignen's process, 267 Porter-Clark's process, 259 Stanhope's process, 261 cost of, 257, 261, 265, 268 purification effected by, 271 saving effected by, 259, 268 Soil, undisturbed, as a filter, 197 influence on typhoid and cholera organisms, 309 Solvent power of water, 5 Sources of supply, 26, 284 Spongilla fluviatilis, 108 Spongy iron, 242, 253 Spring water, 27, 55, 65, 285 Springs, how formed, 57 character of water from, 65 utilisation of, 60 varieties of, 56, 286 yield of, 59, 286 law relating to, 383, 384 Stand pipes, 391 Standards of purity, 191 Stool taps, dangers of, 211 Storage of water, 357 amount of, 298, 360, 366 effect of, 363 of rain water, 21 Strata, chief water-bearing, 72 Streams, vide Rivers Subsoil, permeability of, 42 percolation into, 43 pollution of, 197 by gas, 202 saturation of, 42 water level in, 43 yield of water from, 45, 239, 288, 300 Subsoil water, 27, 41 towns supplied by, 49 movement of, 44 effect upon health, 199 law relating to, 383, 386 Subterranean water, cistern theory, 72 river theory, 72 Sunlight, effect on organisms, 223 Supply, dual, 303 Surface water, 28 Surface water affected by nature of soil, 31 from uplands, 26, 28 cultivated ground, 27, 31 yield of, 34, 294 Tabellaria, 108 Tables Amount of water raised by purnps, 337, 341 nitrates in chalk waters, 166 Analyses of rain waters, 27 deep-well waters, 84, 85 river and other waters, 178 spring waters, 68, 69 subsoil waters, 52, 54 surface waters, 38, 39, 40 Area of filter beds and rate of filtration, 237 Artesian tube wells, yield, etc., 323, 324, 326 Baeteria removed by sand filtra- tion, 228 Cholera death - rate, effect of changed water supply upon, 150 Cost of boring wells, 321 tube wells, 314 Discharge of water from pipes, 355 Effect of subsidence on number of micro-organisms, 227 Efficiency of hydraulic rams, 346 Filtration, rapidity of, 241 Flow of water over notched boards, 288 Force required to work pumps, 340 Quantity of water raised by water wheel, 351 by windmill, 343 per stroke of pump, 337 supplied daily per head, in various towns, 276, 278 by various London Com- panies, 278 yielded by Artesian wells, 323, 326 tube wells, 312, 313 Rainfall, 16 percentage collected in rivers, 93, 94 430 WATER SUPPLIES Tables- Water rates, 416 Well sections around London, 79, 80 Tanks, rain-water, 366, 367 for storage, 367 Taste of water, 2, 111 Temperature of deep -well waters, 322 effect on water in exposed reser- voirs, 363 Towns supplied by lake water, 33, 38 river water, 101 spring water, 68 subsoil water, 49 surface water, 38 deep-well water, 84 Trade winds, 13 Trunk mains, 370, 371 Tube wells, 313, 325 Turbidity of water, 112 Turbines, 347 Typhoid bacilli, influence of soil on, 309 influence of water, etc., on, 191, 223 in drinking water, 186, 187, 191 removal by nitration, 228 Typhoid fever, outbreaks of Ashtou-in-Makerfield, 203 Bangor, 134 Beverley, 135, 177 Bolan Pass, 421 Buckingham, 177 Gains College, 136 Caterham, 134 Chester-le-Street, 138 Croydon, 211, 213 Houghton-le-Spriug, 180 Lausen, 133 Massachusetts, 139, 183 Mountain Ash, 136, 182 Nabburg, 135 Newark, 146, 224 New Herrington, 137 Nunney, 133 Over Darwen, 134 Paisley, 420 Pennsylvania, 212 Sherborne, 136 Tees Valley, 142, 180 Terling, 137 Typhoid fever, outbreaks of Trent Valley, 145, 177 Worthing, 187 UNDERGROUND sources of water, 41, 386 water, advantages of, 78 tanks, 367 Unnecessary consumption, 279 Upland surface waters, 26 Uroglena Americana, 107-108 VARIATION in daily consumption of water, 283 in hourly consumption of water, 277 Velocity of rivers, estimation of, 95 of water in pumping mains, 370 in mains, Eytelwein's formula, 370 Volume of water held by various rocks, 44 WASTE of water, amount of, 280 causes of, 279 detection of, 279 prevention of, 279, 282, 373 Waste preventers, 279, 373 Water tinders, 290 mains (vide Mains) rates, 392, 416 law relating thereto, 390 supplies, Royal Commission Re- port on, 54, 117, 144, 145 208, 216 wheels, 351 works, classification of, 360 Watercourses, vide Rivers Watersheds, 295 available water from, 295, 297 Well sinkers, 305 waters, temperature of, 322 analyses of, 52, 54, 84, 85 pollution of, 49, 197, 203, 305, 421 Wells, Abyssinian, 310 Artesian, 70 cost of, 312 yield from, 312 Wells, construction of, 305 leep, 27, 70, 80 boring and lining, 319 GENERAL INDEX 43 * Wells, deep, cost of boring, 320 effect of pumping on, 78, 293 pollution of, 203, 421 yield of, 80, 82, 292, 303, 325, 326 drainage area of, 44, 289 public, 399 shallow, 46 drainage area of, 44, 293 improved construction of, 306 pollution of, 49, 197, 203 Windmills, 341 YELLOW fever, 153 Yield of water from various sources 285 ZINC in water, 8-10 cisterns, 205-206 effect upon health, 210, 418 Zoo-parasitic diseases, 154 INDEX OF PROPER NAMES ABBOTS LANGLEY, 319, 323 Abel, Sir P., 219 Abergaveimy, 68 Aberystwith, 33, 34, 38 Abyssinia, 155 Adams, 109, 421 Africa, 156 Agra, 242 Aldershot, 318, 323 Algeria, 330 Alnwick, 323 Altona, 232 (vide Hamburg) Anderson, W., 242 An stead, 13 Antwerp, 242 Argentine, 15, 330 Aristotle, 1 Armstrong, Dr., 277 Artois, 71 Ashby, Dr., 412 Ashton-in-Makerfield, 203 Asliton-nnder-Lyne, 415 Assam, 15 Aston, 324 Atherstoue, 69, 276 Attfield, J., 57 Attfield, D. H., 422 Australia, 15, 157 Australia, South, 326 BADDOW, GREAT, 414 Ballard, 133 Bangor, 134 Barking, 276 Barnstaple, 39 Barrow-in-Furuess, 415 Barry, Dr., 90, 103, 129, 142, 419 Batemau, 14, 297 Bath, 59, 165, 415 Batley, 39 Beardmore, 94, 96, 97 Beccles, 313 Bedford, 276 Berlin, 44, 233, 303 Berwick, 275 Beverley, 135, 177 Birkenhead, 84, 415 Birmingham, 278, 415 Bishop-Stortford, 53 Blackburn, 415 Blackston, 15 Blackwell, Mr., 99 Blaxall, Dr., 136 Bolan Pass, 421 Bolton, 108, 415 Bombay, 282 Boston, 39 Boston, U.S.A., 108 Boulnois, P., 282 Boulogne, 242 Bourn, 82, 324 Bradford, 237, 278, 388, 415 Braintree, 166 Brazil, 157 Bridlington, 276 Brighton, 85, 415 Bristol, 60, 65, 68, 276 Broadbent v. Ramsbottom, 380 Brodie, Sir B., 89 Brompton, New, 69 Brussels, 303 Buchanan, Sir G., 136, 175 Buchner, Prof., 421 Buckingham, 177 Buda Pesth, 44, 200 Burnham, 52 Burnley, 415 Burton, 313, 318 434 WATER SUPPLIES Burton, 356, 360 Bury, 415 Buxtou, 2, 38, 59, 165 CALCUTTA, 244, 282 Calkins, J. N., 107 Cambridge, 136, 211, 288 Camden, 263 Canterbury, 85 Cape of Good Hope, 155, 244, 328 Cardiff, 323, 416 Carlisle, 101, 237, 416 Caruforth, 38 Castle Doningtoii, 80, 84 Caterham, 134, 268 Caterham Springs, 57 Cavendish, 1 Chadwell Springs, 78, 288 Chasemore v. Richards, 387, 389 Chatham, 85, 166, 324 Chaux-de-Fonds, 350 Chelmsford, 64, 276 Cheltenham, 59, 68, 103, 109, 416 Chepstow, 68, 276 CheiTaponjee, 15 Cheshunt, 79 Chester, 416 Cliester-le-Street, 138 Chewton Mendip, 60 Chicopee Falls, 142 Chili, 196 China, 15, 70 Cirencester, 323 Clark, Dr., 257 Clark, Professor, 120 Clifton, 59 Clown, 52 Clutton, 384 Colchester, 85, 166 Collins, E., 280 Connecticut, 108 Cornwall, 29 Coventry, 84 Cressbrook, 408 Crookshank, E., 187 Croydon, 135, 200, 230, 213, 301, 387 Cumberland, 14, 29, 118 DALTON, 45 Danbury, 69, 389, 406 Uarenth, 269 Darlington, 101, 181, 416 Dauben See, 56 D'Aubuisson, 97 Dawkins, Boyd, 83 Day, Justice, 398 Deacon, 279 Demerara, 244 Denny, 399 Denton, B., 25, 366 Derby, 416 Derbyshire, 30, 87, 126 Devonshire, 14, 29 Dewsbury, 38, 416 Dibden, 219 Dickenson, 45 Doncaster, 102, 416 Dudley, 416 Dumfries, 237 Duncanson, 278, 375 Dupre, Dr., 190, 219, 270 Durham, 101 EAST HAM, 276 Eaton, 14 Egypt, 155, 157 Elbourne, 52 Ely, 102 Essex, 10, 106, 111, 146, 131, 163, 183, 289, 302 Eton, 158 Eytelwein, 97 Evans, Sir G., 72, 73 Evesham, 52 Exeter, 282, 416 FARLOW, 10 Fedschenko, 155 Fodor, 44, 200 Forschammer, 172 Fraenkel, 48 Frankland, E., 173, 238, 422 Frankland, P., 114, 159, 189, 196, 218, 223, 225, 227, 253, 422 GAKRETT, J. H., 9, 109 Gateshead, 416 Geradin, M., 219 Germany, 157 Gilbert and Lawes, 45 Gininan, 279 Glasgow, 33, 38, 116, 150, 208, 225, 278 INDEX OF PROPER NAMES 435 Gloucester, 102, 110 Gobi, Desert of, 15 Golden Square, 148 Goodie, Dr., 158 Grantham, 68, 276 Gravesend, 313 Grays Thurrock, 288 Greenwich, 15, 16 Grenelle, 71 Gustrow, 221 HALIFAX, 39, 416 Halsbnry, Lord, 388 Halstead, 85, 276 Hamburg, 151, 187, 233 Hamilton, 150 Hampshire, 126 Hanley, 84 Harwich, 77, 85 Hassall, 115 Hawksley, 297, 298, 299 Haynes, Surg.-Capt. , 421 Heaton, Dr. H., 210 Heckmondwike, 38 Kernel Hempstead, 45 Hendon, 158 Henley-on-Thames, 240 Hennell, 238 Hereford, 313 Herrington, New, 137, 198 Hertford, 318, 323 Heybridge, 85 Hey wood, 275 Hicks, Dr., 158 Hirsch, 127, 156 Hodson, G., 77, 78, 80 Holland, Dr., 120 Holmfirth, 397 Honghton-le- Spring, 180 Houston, Dr., 421 Huddersfield, 275, 416 Hull, 416 Humber, Mr., 298 Hunter, 128 ICELAND, 157 India, 151, 156 Ingatestone, 52, 242 Isler and Company, 80, 312, 323 JAPAN, 155 Jessel, M. H., 384 Johnston, Dr., 249 KALAKAN, 15 Katrine, Loch, 33, 35, 225 Keighley, 416 Kelly, Dr., 212 Kempster, Dr. R., 309 Kennedy, 279 Kent, 77 Kentish Town, 77 Kew, 15, 16 Kingsdown, Lord, 385 King's Heath, 323 King's Langley, 45 King's Lynn, 61, 62, 69 Knaresborough, 102 Koch, 48, 49, 51, 151, 190, 196, 198, 229, 231, 233, 309 LANCASHIRE, 8, 30 Lancaster, 416 Latham, Baldwin, 72, 73, 125, 200 Lausen, 133 Laveran, 131 Lawrence, 140 Leamington, 84, 102 Lea Valley (vide Rivers), 79, 82. 223, 226, 238 Le Chapelle, 324 Lech lade, 313, 409 Leeds, 38, 102, 235, 237, 415 Le Grand and SutcliiF, 80, 312, 313, 322 Leicester, 237, 415 Leipsic, 303 Leuckart, 156 Lincoln, 124, 313 j Lincolnshire, 131 ; Liverpool, 33, 39, 75, 79, 225, 261, 278, 281, 283, 325, 415 Llannelly, 210 London, 77, 80, 82, 149, 191, 207, 227, 237, 278, 324 Long Eaton, 80, 84, 124 Low, Bruce, 145 Lowell, 140 Lul worth, West, 350, 411 MACCLESPIELD, 415 Macnaughton, Lord, 389 Madras, 132 Maidstone, 421 436 WATER SUPPLIES Maldon, 85 Manchester, 33, 38, 45, 150, 278, 415 Mansou, Dr., 155 Marseilles, 132 Martin. Baron, 384 Massachusetts, 16, 31, 32, 33, 39, 49, 53, 65, 92, 107, 108, 139, 162, 170, 172, 183, 190, 216, 222, 228, 234, 363 Matlock, 59 M'Clennan, 126 Melbourne, 80, 84 Melrose, 68, 276 Melton Mowbray, 313 Melville. Island, 5 Mendip Hills, 65 Merthyr Tydfil, 39 Mexico, 123 Middlesborough, 101, 180, 275, 415 Miers and Crosskey, 42 Miguel, 20 Millbank Prison, 125 Miller, 208 Mills, 138 Mill wall, 313 Miluer v. Gilmour, 385 Mistley, 156 Moles worth, 340 Monte Video, 242 Montsouris, 20 Morningside, 421 Mountain Ash, 136, 182, 212 Munich, 44, 199, 218, 422 Munro, Dr., 420 Musselburgh, 313 Myelitis, 418 NABBURG, 135 Nantwich R.S.A., 404 Natal, 15 Newark, 102, 146, 224 Newburyport, 141 Newcastle, 277 New Cross, 313 New South Wales, 327 Newton, 49 Northampton, 415 Northumberland, 30 Norton, Cold, 85 Norwich, 52, 76, 85, 166 Nottingham, 126, 176, 415 Nunney, 133 OLDING, Prof., 219 Okehampton, 39 Oldham, 415 Oude, 126 Over Darwen, 134 PAGE, Dr., 135, 137 Paisley, 150 Paris, 89, 156, 219, 350 Parkes, Dr., 132, 273, 289 Parry, J., 364 Patricroft, 323 Pennine Chain, 14 Pennsylvania, 420 Peru, 196 Pettenkoffer, 44, 199, 200 Plymouth, 38, 102, 416 Plynlimmon, 33, 34 Pole, Dr., 297, 298, 299 Poncelet et Lesbros, 100 Pontefract, 84 Poole, 52 Porter, Dr., 298 Portsmouth, 202 Power, W. R., 9, 419 Preston, 38, 416 Procacci, Dr., 421 Pudsey, 127, 208 Purfleet, 313 QUEENSLAND, 322, 325 RAFTER, 108 Rankine, Prof., 273 Rawlinsou, Sir R., 314, 320, 358 Rawtenstall, 52 Reading, 14, 264 Redhill, 134 Kemson, 107 Richardson, Sir B. W., 118 Ripou, 101 Rivers Aire, 56 Bourne, 57 Calder, 102 Chelt, 102 Colne, 324 Danube, 49 Don, 102 Eden, 101 Elbe, 156 Exe, 30 INDEX OF PROPER NAMES 437 Rivers Hamps, 56 Harre, 303 Hooghly, 244 Irwell, 216 Isar, 44, 218 Keimet, 99 Lawrence, 140 Learn, 102 Loddon, 94 Loiret, 56 Manifold, 56 Medway, 94 Merrimac, 106, 141-234 Mersey, 30, 216 Mew, 102 Mimram, 94 Nene, 94 Nid, 102 Ouse, 101, 102, 177 Pleisse, 300 Potomac, 242 Schwarza, 303 Seine, 89, 219 Severn, 94, 102 Sorgue, 56 Spree, 44, 303 Sudbury, 93, 94 Tees, 30, 90, 101, 142, 180 Thames, 14, 88, 89, 94, 102, 117, 216, 219, 222, 223, Trent, 102. 145, 177 Ure, 101 Waudle, 94, 387 Washbnrn, 102 Weir, 101 Wharfe, 102 Yare, 102 Rochdale, 15, 416 Rochester, 325 Rome, 132 Roscoe, Sir H., 4 Rostock, 221 Rotherhithe, 313 Rotterdam, 418 SAFFRON WALDEN, 52, 85, 166, Sahara, Desert of, 15 St. Albans, 319, 323 St. Austell, 68, 276 St. Helens, 278, 416 Salford, 123, 150 115, 256 276 i Sandown, 102 I Scarborough, 416 Schenectady, 124 Scott, 15 Sedge wick, Dr., 142, 418 Sedgley Park, 124 Sheffield, 9, 297, 416 Sherborne, 136 Shields, 14 Shrewsbury, 102 Sleaford, 80, 324 Smith, Angus, 20, 286 Smith, Prof. W. K., 190 Smith v. Archibald, 399 Snow, Dr., 148 Snowdon, 17 Somerville, 12 Sonning, 412 Sonsino, 155 Southampton, 52, 323 Southend, 80, 85, 166 Southminster, 69 Southport, 84, 416 Sowerby Bridge, 15 Springfield, 69, 414 Staffordshire, 30, 56 Staley Bridge, 39 Stampfel, 420 Steeple, 85 Stevens, Dr., 134 Stockholm, 304 Stockport, 298, 323 Stockton, 101, 181 Stoddart, F. W., 167, 168 Stratford, 166 Streatham Common, 80 Stroud, 39, 52, 68, 263 Stye Pass, 15 Sudbury, 85 Suffolk Asylum, 125, 184, 203, 319 Surrey, 77 Sussex, 126 Sutcliff, R., 316 Swansea, 68, 313, 276, 278, 416 Swindon Water Co. , 386 Switzerland, 157 Symons, 13, 18 Syria, 154 TASMANIA, 125 Tegler Lake, 303, 418 Tenterden, Lord, 383 438 WATER SUPPLIES Terling, 137 Tewkesbury, 102, 103 They don Bois, 150 Thirlmere, 33 Thompson, T. W., 419 Thome, 146 Tliorne Thome, Dr., 134, 143, 419 Tidy, Dr., 173, 174, 218 Totnes, 68 Towyn, 38 Tring, 268 Troy, 132 Turner, Dr. G., 125, 126, 184, 319 Tutendorf, 418 Tyler, 279 Tyndall, Prof. T., 114 UNITED STATES, 329 Uruguay, 330 Uxbridge, 324 VAUGHAN, Dr., 158 Venables, Dr., 210 Victoria, 327 Vienna, 303 Vries, Hngo de, 418 Vyrnwy Lake, 33, 225 WAKEFIELD, 102, 237, 244, 416 Wales, 14, 29, 30 Walliugford, 323 Waltham, 49 Waltham Abbey, 79, 80 Walthamstow, 79, 276 Wanklyn, Prof., 172 Ware, 52 Warrington, Dr., 196 Warrington, 323 Watford, 318, 323 Watson, Baron, 384 West Indies, 157 Westmoreland, 14, 29 Weston-super-Mare, 68, 276 Whitaker, W., 61, 72, 79 White, Sinclair, 9 Widford, 313 Wigan, 39 Wightman, Jiistice, 387 j Wildbad, 165 Willesden, 263 Wills, Dr., 224 Wilson, Dr., 127 Wilson, Maclean, 138 Wiltshire, 76 Wimbledon, 156 Wimbome, 323 Winfrith, 410 Winogradsky, Dr., 196 Witham, 156 Wolverhampton, 84, 276, 416 Woodhead, Sims, 250 Woolmer, 288 I Woolwich, 324 Worcester, 102, 103 Worthing, 52, 55, 187, 212, 323 Wraysbury, 313 Wright, Justice, 398 Writtle, 51, 53, 163 YEOVIL, 68, 276 York, 101 Yorkshire, 8, 30, 56 Zurich, 350 THE END Piinfed by R. R. CLARK, LIMITED, Edinburgh UNIVERSITY OF CALIFORNIA LIBEABY, BERKELEY THIS BOOK IS DUE ON THE LAST DATE STAMPED BELOW Books not returned on time are subject to a fine of 50e per volume after the third day overdue, increasing to $1.00 per volume after the sixth day. Books not in demand may be renewed if application is made before expiration of loan period. SEP 24 1931 75m-7,'30 LJ I U /D7