Sewershed Surveillance for COVID-19
Monitoring municipal wastewater and sludge for SARS-CoV-2, the virus that causes the disease COVID-19, along with clinical data on infections and virus shedding rates can provide valuable information to inform COVID-19 epidemiology and the State’s and local health officials’ response to the current COVID-19 pandemic.
Studies have shown that SARS-CoV-2 (COVID-19) variants of concern can be identified in wastewater samples 1-2 weeks prior to being detected in clinical samples from the same area, making wastewater surveillance useful for detecting and monitoring SARS-CoV-2 at the population scale.
The State Water Resources Control Board (State Water Board), in collaboration with the California Department of Public Health, local jurisdictions, and academia, has been collecting and processing data from wastewater surveillance efforts since December 2020. The data collected by the State Water Board is submitted to the California Department of Public Health and subsequently submitted to the National Sewershed Surveillance System (NWSS), a national public health tool used to track the presence of SARS-CoV-2 in wastewater samples collected across the country.
The State Water Board does not require monitoring for SARS-CoV-2, but encourages those that are voluntarily monitoring for SARS-CoV-2 to coordinate with the State Water Board, the California Department of Public Health, and local public health officials to generate and report high-quality data that can be used for decision-making and improve the State’s ability to respond to the current pandemic and prepare for future outbreaks.
In collaboration with our agency partners, the State Water Board is currently monitoring SARS-CoV-2 at the headworks or "influent" of 21 wastewater treatment facilities in the state representing a population of approximately 19 million or 48% of our total population. The following lists the local agency partners participating in this effort:
Data Submittal Questions
The State Water Board will accept data submissions from facilities within California that are willing to collaborate and participate in the surveillance of SARS-CoV-2 in wastewater. All data submitted will be reviewed to ensure it meets the CDC’s NWSS data reporting standards.
For any questions about the data submittal process, please contact OIMA-WBE@waterboards.ca.gov.
Standard Operating Procedures to Measure and Report SARS-CoV-2
In 2018, the State Water Board issued a grant to the Water Research Foundation to convene a group of technical experts to develop, optimize, and validate standard operating procedures (SOPs) to measure a number of waterborne pathogens in untreated wastewater and to develop a Quality Assurance Project Plan (QAPP) that describes quality assurance and quality control (QAQC) measures for the sampling and analyses of the selected pathogens. In March 2020 in response to the COVID-19 pandemic, the Water Research Foundation added SARS-CoV-2 to the project scope and updated the SOPs and QAPP. The QAPP and SOPs for measuring SARS-CoV-2 and the other selected pathogens in untreated wastewater are available on The Water Research Foundation’s page.
The State Water Board strongly encourages laboratories to use this SOP or other SOPs with equivalent QAQC and performance metrics when monitoring for SARS-CoV-2 in wastewater to ensure data quality and reliability.
SARS-CoV-2 Data and Results
The frequency of sampling varies by participating facility but typically three samples a week are collected for raw wastewater analyses and seven samples a week are collected for sewage sludge analyses.
Data is received directly from collaborating laboratories performing the analyses for participating facilities. The data collected includes information related to the sampling events (method of sampling, location, media sampled, etc.) as well as the relative concentration of SARS-CoV-2 in the sample and analytical metadata that supports the analytical results.
All data provided to the State Water Board must meet the data format and standards required by CDC’s NWSS for upload into the national database portal (DCIPHER).
For national wastewater surveillance data, visit the CDC COVID Data Tracker.
To download the California data in machine readable format: Welcome - California Open Data