​Wastewater surveillance, also known as Wastewater-Based Epidemiology (WBE), is a supplementary public health tool that can track the presence and amount of viruses (for instance, SARS-CoV-2, the virus that causes COVID-19), or other disease-causing pathogens in wastewater.

The California Department of Public Health (CDPH) coordinates with local health departments, wastewater utilities, academic researchers, and laboratories in California to monitor for genomic fragments of different pathogens of public health importance in order to improve our understanding of the circulation of different infectious diseases in the community and improve public health surveillance.

Data collected from this network of participants, called the California Surveillance of Wastewater Systems (Cal-SuWers) Network, are submitted to the U.S. Centers for Disease Control and Prevention (CDC) National Wastewater Surveillance System (NWSS).