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.
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.