California-required treatment process removes viruses, including COVID-19

water faucet
Valley News/Courtesy photo

SACRAMENTO – California’s comprehensive and safe drinking water standards require a multi-step treatment process that includes filtration and disinfection. This process removes and kills viruses, including coronaviruses such as COVID-19, as well as bacteria and other pathogens.

The State Water Board’s Division of Drinking Water establishes and enforces drinking water standards that ensure the delivery of pure, safe and potable water. In addition to health-based water quality standards, treatment facilities must comply with stringent performance measures to ensure treatment processes are continuously operating at peak performance.

The treatment process must destroy at least 99.99% of viruses. The limited number that might pass through the removal process are quickly inactivated in the disinfection process, typically in less than 10 minutes. All treatment facilities for surface water sources in California are required to maintain disinfection facilities sufficient to destroy giardia cysts, which are much more resilient than viruses.

COVID-19 is transmitted person to person, not through water, according to the Centers for Disease Control and Prevention.

Public water systems that utilize groundwater sources maintain protective physical measures, including soil barriers, to ensure that water sources are protected from pathogens, including viruses. In addition, most of these systems use chlorine disinfection to inactivate viruses or bacteria that might find their way into the water.

All public water systems in California are routinely monitored for bacteria to ensure that water delivered to customers is free of disease-causing agents. Other parameters, including temperature, pH, turbidity, chlorine residual, electrical conductivity, lead and copper, corrosion indices and disinfection byproducts, are monitored to alert operators about changing water quality conditions and avert potential problems.

The State Water Board works closely with local water systems to ensure the safety of water that flows through public water systems to residential customers.

Contact the local water agencies for more specific information about the drinking water treatment process. Residents can refer to their water bill for their water provider’s website, phone number and email contacts.

In addition, California has established a COVID-19 website with prevention tips all Californians can take to protect themselves from COVID-19 They include staying home, washing hands with soap and water for 20 seconds and cleaning and disinfecting frequently touched objects and surfaces.

Additional resources

For more information and frequent updates about what California is doing to prepare for the impacts of coronavirus, visit the governor’s Office of Emergency Services and the California Department of Public Health.

United States Environmental Protection Agency said, “Americans can continue to use and drink water from their tap as usual.”

For more information, visit

Federal Centers for Disease Control said, “The COVID-19 virus has not been detected in drinking water. Conventional water treatment methods that use filtration and disinfection, such as those in most municipal drinking water systems, should remove or inactivate the virus that causes COVID-19.”

For more information, visit Or The fact sheet was last updated March 19, 2020.

Submitted by California State Water Resources Control Board.