Source: https://www.who.int/publications-detail/water-sanitation-hygiene-and-waste-management-for-covid-19
Q: Does the virus that causes COVID-19 persist in drinking water?
A: While the presence of the virus that causes COVID-19 in untreated drinking-water is possible, it has not been detected in drinking-water supplies. Furthermore, other coronaviruses have not been detected in surface or groundwater sources and, thus, the risk of coronaviruses to water supplies is low.
The virus that causes COVID-19 is enveloped and, thus, less stable in the environment compared to non-enveloped human enteric viruses with known waterborne transmission (such as hepatitis A). One study found that other human coronaviruses survived only two days in dechlorinated tap water and in hospital wastewater at 20°C. In comparison, high levels of removal (>4 log) of the influenza virus were found in drinking-water after contact time of only five minutes and a chlorine residual of 0.3 mg/L. Other studies found similar removals in days to weeks. Significant (99.9%) removal of coronaviruses was observed in two days in primary sewage effluent at 23°C, two weeks in pasteurized settled sewage at 25°C and four weeks in reagent grade water at 25°C. Higher temperature, high or low pH, and sunlight all facilitate virus reduction.
Q: How do we keep water supplies safe?
A: Several measures can improve water safety, starting with protecting the source water; treating water at the point of distribution, collection or consumption; and ensuring that treated water is safely stored at home in regularly cleaned and covered containers. Such measures can be effectively planned, implemented and monitored using water safety plans.
Conventional, centralized water treatment methods that use filtration and disinfection should inactivate the COVID-19 virus. Other human coronaviruses have been shown to be sensitive to chlorination and disinfection with ultraviolet (UV) light. For effective centralized disinfection, there should be a residual concentration of free chlorine of ≥ 0.5 mg/L after at least 30 minutes of contact time at pH < 8.0. A chlorine residual should be maintained throughout the distribution system.
In addition to effective water treatment, water utility managers can adopt several other preventive measures, as part of a broader water-safety planning approach. These measures include ensuring adequate stocks of chemical additives and consumable reagents for water-quality testing, ensuring that critical spare parts, fuel and contractors can still be accessed and that there are contingency plans for staff and training to maintain the required supply of safe drinking-water.
In places where centralized water treatment and safe piped-water supplies are not available, a number of household water treatment technologies are effective in removing or destroying viruses, including boiling or using high-performance ultrafiltration or nanomembrane filters, solar irradiation and, in non-turbid water, UV irradiation and appropriately dosed free chlorine.
Q: How do we safely dispose of greywater or water from washing Personal Protective Equipment (PPE), surfaces and floors?
A: Utility gloves or heavy-duty, reusable plastic aprons should be cleaned with soap and water, and then decontaminated with 0.5% sodium hypochlorite solution each time they are used. Single-use gloves and gowns should be discarded as infectious waste after each use and not reused, and hand hygiene should be performed after PPE is removed. If greywater includes disinfectant used in prior cleaning, it does not need to be chlorinated or treated again. However, it is important that such water is disposed of in drains connected to a septic system, to a sewer, or in a soak-away pit. If greywater is disposed of in a soakaway pit, the pit should be fenced off within the health facility grounds to prevent tampering and to avoid possible exposure in the case of overflow.
Q: What are the water quality and quantity requirements for handwashing?
A: The quality of water used for handwashing does not need to meet drinking-water standards. Evidence suggests that even water with moderate faecal contamination when used with soap and the correct technique can be effective in removing pathogens from hands. However, efforts should be made to use and source water of the highest quality possible (e.g. an improved water source). Reported quantities of water used for handwashing that have enabled reduction of faecal contamination ranges from 0.5 litres to 2 litres per person. Also, the quantity of water used has been associated with less viral contamination of hands. Where water is limited, hands can be wetted with water, the water then turned off while lathering with soap and scrubbing for at least 20 seconds, and then the water can be turned on again to rinse. Water should always be allowed to flow to a drainage area or receptacle, and hands should not be rinsed in a communal basin, as this may increase contamination.