Are specialised water treatment processes necessary?

Conventional centralized water treatment systems which include filtration and disinfection steps should effectively remove or inactivate SARS-CoV-2. Water treatment processes including UV and chlorine disinfection (Study 1, Study 2) are effective against SARS-CoV-1. Centralized systems using chlorine disinfection should ensure a free chlorine residual of at least 0.5 mg/L after 30 minutes of contact time at pH <8.0. A chlorine residual should be maintained throughout the distribution system, whether the system includes piped delivery or delivery via an alternative system like tanker trucks. Where such systems are unavailable, household water treatment (HWT) coupled with safe water storage can be employed to ensure the safety of household stored drinking water. Household water treatment options include boiling, chlorination, ultra- or nanofiltration technologies, and solar or ultraviolet irradiation. Chlorination and irradiation treatments are less efficient in turbid water containing organic matter (soil, other particles) and should be used in combination with technologies which first reduce turbidity (filtration and coagulation/flocculation), or should account for turbidity during dosing. Not all filtration technologies, such as ceramic pot filters, effectively remove viruses from water; ceramic pot filters or biosand filters should therefore be coupled with additional treatment options such as disinfection with chlorine or irradiation. Before promoting any specific HWT technology, ensure it has demonstrated effectiveness against a range of viruses, including human coronaviruses where possible. The WHO has evaluated many HWT options and provides an overview of their performance against different types of pathogens in this report. Benefits and drawbacks of different technologies are also summarized on the CDC website.  

Author: Jackie Knee
Review: Tom Heath, Robert Dreibelbis, Oliver Cumming, Karin Gallandat, Kate Medlicott
Last update: 13.08.2020