key: cord-0835311-cgdzsk8e authors: Langone, M.; Petta, L.; Cellamare, C.M.; Ferraris, M.; Guzzinati, R.; Mattioli, D.; G, Sabia title: SARS-CoV-2 in water services: presence and impacts() date: 2020-10-13 journal: Environ Pollut DOI: 10.1016/j.envpol.2020.115806 sha: 5db0e95c1cbf2dc985cd60e871c8acdb4d1bd683 doc_id: 835311 cord_uid: cgdzsk8e The occurrence of human pathogenic viruses in aquatic ecosystems and, in particular, in internal water bodies (i.e., river, lakes, groundwater, drinking water reservoirs, recreational water utilities, and wastewater), raises concerns regarding the related impacts on environment and human health, especially in relation to the possibility of human exposure and waterborne infections. This paper reviews the current state of knowledge regarding severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) presence and persistence in human excreta, wastewaters, sewage sludge as well as in natural water bodies, and the possible implications for water services in terms of fecal transmission, public health, and workers’ risk. Furthermore, the impacts related to the adopted containment and emergency management measures on household water consumptions are also discussed, together with the potential use of wastewater-based epidemiology (WBE) assessment as a monitoring and early warning tool to be applied in case of infectious disease outbreaks. The knowledge and tools summarized in this paper provide a basic information reference supporting decisions makers in the definition of suitable measures able to pursue an efficient water and wastewater management and a reduction of health risks. Furthermore, research questions are provided in order to address technical and public health communities towards a sustainable water service management in the event of a SARS-CoV-2 re-emergence, as well as a future deadly outbreak or pandemic. On 31 December 2019, the China Country Office of the World Health Organization (WHO) was alerted to a 37 cluster of pneumonia cases of unknown aetiology in Wuhan City, Hubei Province of China (WHO, 2020a). On 38 9 January 2020, Chinese authorities confirmed that they had identified a novel (new) coronavirus as the 39 cause of the pneumonia (XinhuaNet, 2020). The International Committee on Taxonomy of Viruses (ICTV) 40 named the virus as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and the disease as 41 COVID-19 (Gorbalenya et al., 2020) . SARS-CoV-2 has spread globally, and currently (as of 27th September 42 2020), according to the daily report of the WHO, the world registered over 32.7 million confirmed cases and 43 991,000 deaths in 146 countries (WHO, 2020b) . This dramatic world health emergency is a clear example of 44 the new problems and challenges related to a rapidly changing world. In order to minimize negative impacts 45 on human health, environment and economy, it is crucial to reduce transmission routes and risks of 46 contagion and promote suitable policies aimed at improving the rational use of natural resources, the 47 sustainability of production processes and environmental protection. Actions addressed to a rational 48 management of water resources, wastewater, and waste should be included into an overall strategy aimed 49 at tackling the impacts of the pandemic. 50 Coronaviruses (CoVs) belong to the Coronaviridae family in the order Nidovirales, and are further subdivided 51 into four genera, the alpha (α), beta (β), gamma (γ) and delta (δ) coronavirus (Fehr and Perlman, 2015) . 52 CoVs are minute in size (65-125 nm in diameter) and are single-stranded, positive-sense, non-segmented 53 enveloped RNA viruses (Baker et al., 2011) . The surface has various corona-or crown-like spikes, which are 54 helpful to attack and bind living cells, which give them the appearance of a solar corona, prompting the 55 name, coronaviruses. CoVs are host-specific, and can infect a variety of different animals (including camels, 56 bats, pigs, cows, chickens, dogs, and cats ) (Fehr and Perlman, 2015) , as well as humans, causing several 57 diseases with varying severity (Zumla et al., 2016) . In humans, the viruses can cause mild to moderate 58 illnesses, ranging from the common cold to acute respiratory infections (Fehr and The current global crisis clearly underlines the critical importance of water management and sanitation 70 within an effective world health system. With regard to the COVID-19 emergency, appropriate water 71 management is essential in the prevention of contagion (WHO, 2020c) and surveillance through monitoring 72 of sewer systems (Mao et al., 2020b) , while water itself may represent a potential means of transmission 73 (WHO, 2020d). Consequently, water services, as an indispensable element for human development, welfare 74 and health, play the fundamental role to guarantee safety and quality in drinking water supply as well as in 75 wastewater collection and treatment management. overview on the all components of the water system is missing. This paper reports recent research on the 80 presence and persistence of SARS-CoV-2 in wastewaters, water and sludge. The possible implications for the 81 water service in terms of fecal transmission, human exposure, public health and workers risk are discussed. 82 Furthermore, the impacts of containment measures and emergency management on household water 83 consumptions are also analyzed, together with the potential of wastewater-based epidemiology (WBE) as a 84 monitoring and early warning tool to be applied in case of infectious disease outbreaks. This review is based 85 on current knowledge on the SARS-CoV-2, focusing on its presence and impacts in water service. Current 86 research information may be useful to support technician and local authorities to evaluate risks inherent to 87 the adequacy of the wastewater collection and treatment systems, the disposal of the generated waste (i.e. 88 sludge, grit, grease, oil) as well as for the development of guidelines in water service management, such as 89 the sanitation safety plans -SSP (WHO, 2016). 90 Studies reported in this paper include research articles, reviews, short communications, editorials, case 92 reports, case series, news and others. More accurately, in order to collect specific information on the SARS-93 CoV-2 in water service, literature has been searched by combining keywords with the Boolean operators 94 "AND". assess the probability of contagion through such a mechanism, a distinction must be made between indoor 120 environments with lacking air exchanges and outdoor environments. However, the effective probability of 121 contagion depends on different factors, including the concentration and the size distribution of virus-laden 122 aerosols in air, the chemical and biological composition of the bioaerosol, the lifetime of the virus, and the 123 minimum amount of viable virus needed to be inhaled to produce infection. 124 Finally, a possible fecal transmission of the virus has been hypothesized (Amirian, 2020; Ding and Liang, 125 2020). The WHO in a technical report has stated that the risk of contracting the SARS-CoV-2 from the feces 126 of an infected person seems to be low (WHO, 2020c The occurrence of SARS-CoV-2 has been showed in stool samples of symptomatic and asymptomatic people 142 (Rampelli et al., 2020) However, in these studies there are no data relating to virus infectivity, but only the presence of fragments 204 of RNA is reported, and further research studies are required. However, for sludge produced during the 205 COVID-19 pandemic that has not undergone any disinfection treatment, there are not enough data available 206 to be able to define the level of contamination by SARS-CoV-2. 207 Finally, the presence of CoVs in natural water systems has been experimentally evaluated in a small number 208 of studies, as reviewed by La Rosa Metropolitan area, Italy, during the COVID-19 peak disease, probably due to untreated wastewater 214 discharges or sewage overflows. However, virus infectiveness was not significant, indicating the natural 215 decay of viral vitality. The WHO, in its technical report o, has stated that the presence of SARS-CoV-2 has 216 not been observed in drinking water supplies and concluded that the risk for water supplies is low (WHO, 217 2020g). The EPA recommends to continue using and drinking tap water as usual (EPA, 2020a). However, 218 SARS-CoV-2presence in drinking water remains a major concern for the water sector. In countries with a 219 highly developed water supply system, it is difficult for viruses to overcome the existing stages of filtration 220 and disinfection. On the contrary, in countries where water treatment is not equipped to remove viruses, its 221 presence is unknown. 222 The to 2 days at 37°C, to 30 min at 56°C, and 5 min at 70°C. 239 Concerning disinfectants, chlorine rather than chlorine dioxide has been found to be more effective in system is depicted in the Supplementary information section (Fig. S1 ). 252 Water service can play a critical role during pandemics, preventing or amplifing disease transmission. 254 Currently, it is known that SARS-CoV-2 once expelled from the host, can survive for just a few days in the 255 environment out of living cells (Y. , but enough to reach other living organisms, and to be 256 transferred from one compartment to another. 257 compartments, and consists of all services connected to the human use of the water resource, from 259 "abstraction, impoundment, storage, treatment and distribution of surface water or groundwater", to 260 "wastewater collection and treatment facilities which subsequently discharge into surface water". An 261 overview of the water services in Europe in relation to the potential risk of SARS-CoV-2 transmission is 262 provided in Supplementary Information. When proper prevention measures and adequate treatments are 263 implemented in water management systems SARS-CoV-2 contamination risks are limited. 264 Fig. 1 summarizes the fate of SARS-CoV-2 in water services, highlighting potential routes of contamination. 265 The level of risk rises in cases of inadequate water, sanitation and hygiene management. (A) Sources of drinking waters (i.e. surface water and groundwater) may contain viruses due to 267 contamination with infected waste and wastewater. This risk is to be taken into account expecially in 268 cases of illicit wastewater discharges into surface water bodies exploited as sources for drinking 269 water production. contamination may exist in case of leaks in underground pipelines and low dynamic pressure in 276 water distribution system. Exposure through aerosols or direct contact is limited to professional 277 workers. (D) Drinking water consumers are potentially exposed to viruses if water treatments are not properly 279 efficient and the distribution systems reveal structural weaknesses. However this risk is very low. (E) Viruses are excreted in feces, urine, and vomit of symptomatic and asymptomatic people. Given the 281 survival time of SARS-CoV-2 RNA nucleic acid-positive, attention should be paid to personal hygiene 282 (e.g. washing, disinfection) and sanitation practices. Particular regard should be given to busy places 283 such as hospitals, rest homes, shopping centres, offices. (F) Where greywater reuse is practiced particular attention should be paid to a potential transmission 285 risk due to the virus persistence on domestic surfaces (eg. ceramic sink, plastic toilet seat). (G) Where rainwater reuse is practiced, particular attention should be paid to potential transmission 287 routes due to the virus persistence in environment and aerosols. (H) Viruses excreted in feces, urine, and vomit enter into the sewage system. In the municipal sewage 289 system there can be either an airborne transmission, especially in the points where areosols are 290 produced, such as pumping stations, or a contamination of underground drinking water distribution 291 systems, water surface resource, soil, etc. due to leaks in underground sewage pipes. However, 292 exposure through aerosols or direct contact is limited to professional workers if not adequately 293 protected by personal protective equipment (PPE). (I) Inside buildings, where water or aeration networks present inadequate systems or operations, risks 295 are to be linked to airborne or direct contact transmission. (J) The interconnectedness of the wastewater plumbing network in high-risk transmission settings such 297 as hospitals and health-care buildings have to be strictly monitored, as it may facilitate exposure to 298 SARS-CoV-2 299 (K) Sewage overflow (CSOs) events lead to the release of infective viruses to surface waters. 300 (L) Septic tank used in isolated buildings may contain viruses with subsequent risks for purge service 301 operators and any subjects close to the places of operation. (M) Illicit discharges can cause potentially contaminated wastewaters to flow directly into the receiving 303 water body, impacting drinking waters and bathing waters. (N) Wastewaters are transported to WWTPs to be treated before the final discharge into the 305 environment. The adopted treatments must result to be able to reduce virus levels and activity. 306 Infective human viruses have been detected in WWTP streams mainly before disinfection treatment. 307 Plant operators may be exposed to infective viruses in the case of contacts with raw wastewater, 308 primary and secondary effluents as well as sewage sludge. Workers are adequately protected 309 wearing personal protective equipment (PPE). (O) Inadequate wastewater treatments can result in viruses discharging into surface waters impacting 311 drinking waters and bathing waters. (P) Illicit discharges, CSOs and WWTP effluents would possibly impact recreational activities, such as 313 bathing. 314 (Q) Residual biosolids from WWTP are disposed, often via land-application, composting, incineration, 315 landfill. Workers in close contact with residual biosolids may be exposed to infective viruses that 316 have survived the solids treatment. (R) Particular attention must be paid to municipal sludge reuse in agriculture and agronomic spreading 318 of livestock effluents. (S) Particular cautions should be paid to treated wastewaters reuse practices. 320 (T) In order to limit the risk of virus spreadings, attention has to be paid to communities with poor 321 quality or untrusted residential water infrastructure. In this study, a roadmap for a safe management of water services during pandemics has been developed, 325 analyzing the drinking-water supply, the fecal, wastewater and sludge management. 326 Securing the safety of drinking-water supplies is based on multiple barriers, from catchment to consumer. 328 The first step to prevent drinking water contamination is the adequate protection of water reservoirs. In 329 order to achieve this objective, it is mandatory to prevent surface and underground waters from coming into 330 contact with fecal material, especially human feces, which represents one of the main source of potential 331 Sars-Cov-2 contamination. Surface waters are more susceptible to having CoVs contamination than 332 groundwater, because the latter benefits from the pathogens removal due to soil filtration, adsorption on 333 sediment grains and progressive inactivation, which increases with the time necessary to reach the aquifer. 334 Nevertheless, viruses in surface waters are exposed to several potentially inactivating stresses, including 335 sunlight, oxidative chemicals, and predation by microorganisms. The protection of water reservoirs also 336 depends on adequate wastewater treatments. 337 Further, to ensure greater safety, an adequate drinking water treatment is required. Conventional 338 centralized water treatment plants, employing filtration and disinfection, appear to be sufficient to inactivate 339 the SARS-CoV-2 (WHO, 2020c). Research on other human CoVs and on different and more persistent viruses 340 has shown high sensitivity of viruses to chlorination as well as to disinfection with ultraviolet (UV) light 341 (University of California -Santa Barbara, 2020). Recently, plasma discharge technology has been proposed 342 for removing CoVs (Ghernaout and Elboughdiri, 2020). However, in order to guarantee the safety of drinking 343 water supply during and after a lockdown, disinfection performance must be continuously monitored (i.e., 344 turbidity, disinfectant dose, residual, pH, temperature, and flow). For an effective centralized disinfection 345 with chlorine, the residual concentration of free chlorine should be more than 0.5 mg / L after at least 30 346 minutes of contact time at pH < 8.0. A chlorine residue must be maintained throughout the distribution 347 system. 348 Researches on the efficacy of emerging disinfection technologies for CoVs inactivation, especially treatment 349 steps that are integrated into drinking water reuse, including UV-based advanced oxidation processes 350 (UV/AOPs) and ozone/biologically activated carbon (O 3 /BAC), are needed (Naddeo and Liu, 2020). Moreover, 351 legislation and guidelines for virus removal in drinking reuse systems need to be reviewed taking into 352 account pandemic events. 353 In order to prevent any recontamination of the treated water, it is necessary (i) to avoid leaks in the drinking 354 water networks and drops in pressure in the pipes in order to prevent pontentially contaminated water from 355 other sources from entering; (ii) to better understand the role of bacterial colonies and biofilm in drinking 356 waters networks in hosting viruses and affecting their viral stability; (iii) to ensure a safe and clean storage 357 of drinking water, if it is to be conserved. In places where centralized water treatment are absent and drinking water supplies are not available, 359 protection measures and regular maintenance of wells and septic tanks are recommended. Domestic water 360 treatment can be used as an additional defense measure, particularly in the periods following intense rains, 361 which increase the risk of possible wells contamination. Various domestic treatment technologies are 362 recommended, effective in the removal or inactivation of viruses, including boiling water, or the use of 363 membrane filtration of suitable molecular cutting, solar radiation and, in absence of water turbidity, or after 364 adequate solid removal, UV radiation and appropriately dosed free chlorine (WHO, 2020). 365 By following these precautions and considering the characteristics of the virus, it is highly unlikely that 366 drinking water could turn into a transmission vehicle for SARS-CoV-2, which in fact has never been detected 367 in drinking water to date. Based on the current evidence, the risk to water supplies is low in countries with 368 high-quality residential water infrastructure (EPA, 2020b). 369 Attention should be paid also to water supply in buildings that have been closed for weeks or months during 370 lockdowns, where stagnant water can be accumulate inside building plumbing, increasing the risk of 371 pathogens transmission. This water can become unsafe to drink or otherwise use for domestic or commercial 372 purposes. Actions to minimize water stagnation during closures should be adepted by building owners and 373 managers to address building water quality prior to reopening. 374 As far as wastewater is concerned, correct management of wastewaters must necessarily start from the 376 collection. Wastewaters from hospitals and isolation centers treating SARS-CoV-2 patients as well as 377 domestic sewage from areas of known and unknow contamination may have elevated concentrations of 378 viruses, and require particolar attention. Nevertheless, a recent study confirmed the low risk of 379 contamination, when wastewater is adequately managed (Rimoldi et al., 2020). 380 Nevertheless, regards must be paid to preventing leaks from sewage systems, in order to avoid human 381 exposure to pathogens and to prevent the contamination of surface and underground water reservoirs. A 382 potential risk of viral contamination of receiving waters is further related to the discharge of combined 383 sewage owerflows (CSOs) during heavy meteoric events, as untreated wastewaters are disharged together 384 with rainwaters into natural environment ( has asked WWTPs to strengthen their disinfection routines (mainly through increased use of chlorine) to 404 prevent the new CoVs from spreading through wastewaters. Nevertheless, potential ecological impact of 405 disinfection by-products present in chlorinated wastewater effluents has to be taken into account, and 406 research on environmental friendly disinfection treatments to remove viruses should be carried out. Even if potential infection risk due to accidental contacts with wastewaters (e.g., airborne aerosols and 408 droplets) seems to be negligible, WHO highlights the need to adopt best practices for the protection of 409 workers' health in wastewater treatment facilities, pumping out tanks or unloading pumper trucks (WHO, 410 2020c). All workers should wear adequate personal protective equipment (PPE), including protective 411 clothing, gloves, boots, protective glasses, or a visor and a mask. They should frequently perform hand 412 hygiene and they should avoid touching eyes, nose, mouth and food with unwashed hands. 413 Finally, In order to minimizing health and hygiene risks related to wastewater reuse mainly in agricolture, a 414 deeper knowledge on SARS-CoV-2 viability in reused water is needed. Wastewaters from health facilities 415 should never be reused or released on land that is used for production of food or disposed of in recreational 416 waters (WHO, 2020c). 417 Sewage sludge deriving from primary sedimentation (primary sludge), secondary sedimentation after 419 biological treatment (secondary sludge) and clariflocculation (chemical sludge) are biologically unstable 420 materials that have to be treated to reduce the content of biodegradable organic substances, the water 421 content as well as the microbial and pathogenic load. Fragment of SARS-COV-2 genetic material has been 422 detected in primary sewage sludge, but no data are available on its viability (Peccia et al., 2020 Recently the presence of SARS-CoV-2 have been found in primary sludge, a well-mixed and concentrated 491 sample that may be advantageous for monitoring SARS-CoV-2 (Peccia et al., 2020). The virus RNA 492 concentrations were highly correlated with the COVID-19 epidemiological curve and local hospital 493 admissions. This would imply the development of a raw wastewater and sludge-based epidemiology 494 surveillance approach. Given the high cost of COVID-19-related lockdowns (Nuno, 2020) , having information available in real-time 496 to inform policy would have substantial economic value. The challenge thus becomes to design a widely-497 accepted surveillance system to detect the potential community presence of COVID-19, in order to collect 498 data to support politician decision-making processes (Sims and Kasprzyk-Hordern, 2020), helping both 499 during COVID-19 reopening plants, defining restrictions on population movement (e.g. social distancing and 500 city-wide lock down) or re-open commerce and to prevent SARS-CoV-2 re-emergence (Fig. 2) . Data from 501 massive virus surveillance from sewers can be coupled with health and socio-economic data under an unique 502 National Digital Epidemic Observatory by using Machine Learning to link various data sources and optimize 503 early warning and mitigation measures. WBE's limitation related to identify infected individuals and their 504 specific locations can be overcome by suitable sampling campaigns, that can allow to implement a first 505 qualitative step of an effective surveillance, followed by a clinical testing that serves to identify infected 506 individuals in WBE-revealed hotspots (Hart and Halden, 2020) . 507 Governments worldwide and National agencies should encourage the implemetation of WBE. European 508 Commission's Joint Research Centre and the Directorate-General for Environment have issued a call for 509 participation in European Action investigate the development of the WBE approach for SARS-CoV-2 510 surveillance, exchanging experiences among utilities, research centers, universities, governments (European 511 Commission, 2020). Up to date, numerous european stakeholders (international, national, regional and local 512 activities) are working in parallel, with different designs and approaches, collaborating to solve challenges 513 related to sampling, analytical methodology, interaction with health services and epidemiologists, data 514 hosting and decision support, and knowledge transfer and international exchange. The severity of the COVID-19 pandemic has forced almost all world countries to observe extraordinary 519 measures to tackle the exponential virus spread. In absence of a specific vaccine formulation, the first 520 measures that has been possible to adopt are those aimed at limiting the contagion phase through social 521 distancing, closure of educational centers, restriction of social activities and public life, lockdown of many 522 commercial and work activities or, where possible, their remodulation with new tools such as smart working 523 as well as the recommendation to take special hygienic and sanitary measures, focused on handwashing, 524 cleaning and disinfecting to prevent COVID-19. 525 These measures heavily weigh on our behavior. Indeed, after many States around the world had issued 526 stay-at-home orders, a very high percentage of people has been forced to stay the whole day at home, with 527 consequences for the entire water sector, starting from drinking water consumption in homes to the quality 528 and quantity of municipal wastewater, the possible effects to be assessed on WWTPs, on water bodies and 529 public health and operators in the sector. The consequences on water sector are further compounded by the 530 adopted cleaning and disinfection measures of external environmental surfaces (i.e. streets, urban 531 pavements) and environments in healthcare and nonhealthcare settings (ECDC, 2020). 532 If it is plausible that the measures to combat the COVID-19 pandemic lead to inevitable increases in water 533 consumption on the domestic side, it is also, on the contrary, to consider that during the lockdown the 534 forced arrest of countless industrial water-intensive activities c induces a strong reduction. Obviously the 535 overall effects on the national water systems are difficult to quantify and can only be verified with the 536 collection of real consumption data generated in the quarantine period, and after it, with the support of 537 water utilities around the world. However, trying to quantify the changes in consumption induced at the 538 domestic level can be an indication of how much they can weigh on families and, through greater 539 awareness, give ideas on a better approach in the use of water resources. 540 Among the measures for COVID-19 epidemiological emergency containment and management there are, as 542 mentioned, measures that limit the movement, impose social restrictions and require home quarantine of 543 infected or potentially infected subjects as well as sanitary prevention measures including the following 544 recommendations: washing often hands with soap and water or with a hydroalcoholic solution; clean the 545 surfaces with chlorine or alcohol based disinfectants; in the case of infected patients, washing clothes, 546 sheets, towels in the washing machine at 60-90 ° C, as well as using disposable paper towels (WHO, 2020c, 547 2020g). 548 The confinement in houses together with the greater demand for sanitation has a possible significant impact 549 on household water consumption. A rough estimation of the increase in water consumption associated with 550 a greater presence of the residents at home has been made from data collected as part of an our European 551 project on rational use and re-use of water in residential buildings (ENEA, 2001) . After the realization of the 552 project, in the period 2012-2014, a 3-years of monitoringwater consumption has been carried out on an 553 entire building consisting of 8 apartments in Italy. Results showed that water consumption exhibited a 3-4 554 fold increase depending on different behavioral modalities. The highest values of water consumption have 555 been recorded for older people as compared to younger people (about 200 and 55 L/day/person for an 556 average age of the residents of 60 and 25 years old, respectively) (Fig. S2) . This result has been related to 557 the fact that elderly people stay as long as possible in their homes during the day since they do not have 558 work and / or school needs. Based on this result, it can be hypothesized that the continuous presence in the 559 house induced by the lockdown can therefore lead to more than three times water consumption in those 560 families who normally live most of the day outside the home. 561 This estimation is supported by the raise of the average water consumption per capita in buildings calculated 562 as consequence of recommendations to increase handwashing frequency. Considering 12 additional daily 563 washes and 40 seconds each washing operation, handwashing practice will result in an extra daily water 564 consumption of about 25-96 L/day/person, depending on tap type (e.g. aerators, starndard, flow reducer) 565 and water saving measures (see Supplemental Information and Table S1 ). Even higher consumption must 566 be expected if handwashing is performed by means of hot water, because in this case more water is 567 generally wasted waiting to reach the desired temperature. The use of hot water (about 40°C) to reduce 568 virus and bacteria during handwashing is a habit also to increase comfort during the operation (Sickbert-569 Bennett et al., 2005). However, some studies have highlighted how cleaning efficiency is closely linked to 570 the quality of the soaps used and the prudence and obstinacy with which hands are scrubbed rather than 571 the water temperature (Laestadius and Dimberg, 2005; Michaels, 2001; Michaels et al., 2002) . Furthermore, 572 a higher domestic water consumption should also be linked to the higher frequency of laundry washing and 573 dishwashing, which are two everyday household activities that, in normal conditions, account for 574 approximately 20% of the household water consumption (Schleich and Hillenbrand, 2009 ). 575 Changes in daily water consumption patterns have been also observed, due to the closure of schools and 576 non-essential activities and the increase in home-working. Data on daily water consumption profile in a 577 German city have been published by a water utility (WatEner, 2020). Under normal situation (3 March 2020, 578 before COVID-19 measures) the demand peak occured at around 7.10 am, when schools and activities were 579 open, with a higher slope of water consumption curve as compared after the restriction measures were 580 adopted (24 March 2020), when the demand peak occurred approximately two hours later. Furthermore, 581 before lockdown, water consumption was minimum after 8:00-8:30 until late afternoon (16:00-17:00), while 582 during the quarantine period, water consumption was distributed more gradually in the morning, reducing 583 slowly until the afternoon. Moreover, data showed that between 17:00 and midnight, there were no 584 significant differences in consumption before and after the containment measures, indicating that consumers 585 behavior was not altered during this time. In order to limit as much as possible, the impact in terms of greater domestic water consumption due to the 587 ongoing health emergency, it is important, on one hand, while following hygienic recommendations, try to 588 limit the use of water as much as possible in order to not stress the drinking water distribution system and 589 wastewater management system. In this regard, it should be considered that in public places only taps with 590 pedal or automatic start&stop and dispensers with photocell should be provided, which have the advantage 591 of not requiring direct contact with hands together with save water. This aspect shoud be taken into account 592 expecially in areas where drought occurs. 593 Graywater recovery technologies (i.e. water deriving from the drains of showers, washbasins etc.) should be 594 encouraged, as they could allow drinking water savings for those uses where it is not strictly necessary. 595 Nevertheless, some critical aspects should be kept in mind in the case of graywater reuse during sanitary 596 emergency conditions, like those occurred with the COVID-19 pandemic. Graywater recovery systems 597 usually undergoes a 3-to 4-stage treatment based on separation and disinfection processes, whose 598 effectiveness against the virus is to verify. For a correct risk assessment, it would be necessary to carry out 599 J o u r n a l P r e -p r o o f additional research. Minor critical issues are instead conceivable in the case of using rainwater recovery 600 systems, once a check on the actual residence times of the virus on the external surfaces have been 601 established. 602 The recommendations provided to deal with the emergency of the COVID-19 epidemic may also have an 604 impact on the quality of wastewaters, the environment, and eventually may compromise the quality of 605 drinking water. This aspect is mainly related to the cleaning and disinfection operations of surfaces of indoor 606 and outdoor environmets. Several studies have evaluated the persistence of the SARS-CoV-2 on different 607 surfaces ( been tested specifically on SARS-CoV-2, but they are expected to be effective because they have been 633 tested and proven efficient on either a harder-to-kill virus or another human coronavirus (EPA, 2020c). 634 However, the selection of disinfectants should take into account toxicity and impacts on environmental and 635 human health. Spraying or fogging of formaldehyde and chlorinebased or quaternary ammonium 636 compounds, is not suggested due to negative health effects on workers in facilities where these products 637 have been previously utilized (Schyllert et al., 2016) . The use of hypochlorite-based products, including 638 sodium hypochlorite (liquid) and calcium hypochlorite (powdered or solid), should be carried out carefully. 639 Hypochlorite-based products are, indeed, dangerous substances, and are responsible for cause serious skin 640 burns, eye injuries and respiratory irritation. It is also very toxic to the aquatic environment, both in the 641 short and long term (APA, 2020). Moreover, this substance, in the presence of organic materials present on 642 surfaces, could also give rise to the formation of extremely dangerous by-products, such as chloramines and 643 trihalomethanes and other volatile carcinogenic substances and dangerous non-volatile by-products (WHO, 644 2004). 645 Besides touchable surfaces in indoor environments, in order to protect the public health, some governments 646 have addressed the issue related to the cleaning and disinfection of outdoor spaces and road surfaces, 647 spraying disinfectant on the streets and in marketplaces. Nevertheless, outdoor spaces disinfection is not 648 recommended by WHO to kill the SARS-CoV-2, because it does not eliminate the virus, mainly due to the 649 fact that disinfectants are inactivated by dirt and debris and, further, the adequate contact time to inactivate 650 pathogens is not guaranteed (WHO, 2020h). This practice even poses a human health (Benzoni and 651 Hatcher, 2020; Mehtar et al., 2016) and environmental pollution risk. Some countries underline the 652 opportunity to wash street and urban pavements with ordinary cleaning by means of water and conventional 653 detergents -avoiding the production of dust and aerosols, and to limit disinfection with products such as 654 sodium hypochlorite to exceptional interventions and on limited areas (ISS, 2020b). Sodium hypochlorite 655 may affect the quality of surface water as well as the quality of groundwater if it reaches these areas 656 through wastewaters not previously treated in WWTPs. Furthermore, attention must be paid to areas served 657 by sewage with subsequent wastewater treatments. In WWTPs, an excessive use of sodium hypochlorite 658 may compromise the functionality of biological processes, with negative consequences on quality of the final 659 effluents. Finally, another aspect to take into account in sewage and WWTPs management is the overload of 660 the sewage system due to a possible greater presence of disinfectant wipes, toilet paper and other similar 661 products that may have been mistakenly thrown into the toilet due to COVID-19 emergency. All these 662 aspects should be investigated in collaboration with water utilities who provide both water and sanitation 663 services. 664 Many research studies have been carried out during SAR-CoV-2 pandemic, each with its own contribution in 666 terms of understanding and defining the potential role of the water services in the spread of the virus. A 667 roadmap for a safe management of water services has been developed in this study.According to the 668 evidences highlighted in the present paper, it is possibile to identify a series of key aspects and 669 recommendations that are worth being taken into consideration and to be deepened extended and improved 670 in order to further progress with the status of knwoledge related to SAR-CoV-2 pandemic: 671 • Access to safe drinking water and sanitation services, especially for vulnerable communities, has to 672 be improved and guaranteed. 673 • Water distibution systems and wastewater collection infrastructures have to be optimized, reducing 674 pipe leaks, CSOs, illicit discharges. 675 • Methods for SARS-CoV-2 detection (concentrating, extracting and purifying) from complex sample 676 matrices such as wastewater, residual biosolids, and surface water need to be optimized and 677 standardized. In this regard, specific methods and procedures need to be developed and defined. 678 • Further research activities regarding the viability, infectivity and persistence of SARS-CoV-2 in 679 feaces, urine, raw wastewater, and sludge, are required. 680 • Water and wastewater treatment plants should be handled in a preventive manner. 681 • In order to have a systematic approach in pandemic surveillance, the water sector should be 682 integrated with the other sectors, such as local health officials and other relevant bodies. 683 • The "sewage epidemiology approach" should be considered together with the "wastewater 684 epidemiology approach", and coupled with health and socioeconomic data, as a first qualitative step 685 of an effective surveillance, followed by a clinical testing that serves to identify infected individuals. • Quantitative risk assessments should be conducted for SARS-CoV-2 in wastewater, recreational 687 water utilities and drinking waters. 688 Such research issues are also critical in order to increase the public awareness and technical knowledge and 689 to set-up sustainable water services management in the event of a SARS-CoV-2 re-emergence, as well as of 690 future deadly outbreaks or pandemics. 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