Wastewater, or sewage, is the ādirty" or used water that is generated from homes (from toilets, sinks, kitchens, showers, laundry, etc.) and from facilities like restaurants, schools, offices, or industrial buildings. It is not potable or drinking water. Wastewater is collected through a series of pipes and drains and transported to a wastewater treatment plant (WWTP) where it is cleaned and treated before being safely returned to the environment. Note that not all industries, facilities, or homes will contribute wastewater to a wastewater plant, as some wastewater is collected in septic systems or lagoons, not permitted to be released into a wastewater treatment plant, or otherwise managed separately.āÆ
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The sewershed of a wastewater treatment plant refers to the area that is serviced by that wastewater treatment plant through a network of pipes, sewers, and manholes. This area is also sometimes referred to as a catchment area. (return to top of page)ā
The sewershed of a wastewater treatment plant refers to the area that is serviced by that wastewater treatment plant through a network of pipes, sewers, and manholes. This area is also sometimes referred to as a catchment area.
Wastewater surveillance, also known as Wastewater-Based Epidemiology (WBE), is a public health tool that can test for genomic fragments (e.g., pieces of RNA or DNA) of infectious pathogens (e.g., viruses, bacteria, fungi) in untreated wastewater samples. Samples for wastewater surveillance are generally collected as the wastewater enters a wastewater treatment plant before it begins the treatment process in which microbes, contaminants, and debris are removed from the wastewater. Testing these wastewater samples can provide additional understanding about the presence or spread of diseases within a community to supplement other sources of public health information. For example, people infected with SARS-CoV-2, the virus that causes Coronavirus disease 2019 (COVID-19), can shed the virus in their feces for several days before they are able to get tested. Those viral fragments get flushed down the toilet where it gets mixed together with sewage from the entire community. By taking a small sample of wastewater at the wastewater treatment plant and looking for how much viral material is in it, wastewater surveillance can quickly provide public health with information about how much COVID-19 is impacting the entire community. This type of public health monitoring tool can provide useful information even as people change their testing habits over time and can sometimes provide early warning of increased disease activity. This information can help provide important information to help prepare public health, the community, and the healthcare system. (return to top of page)ā
Wastewater surveillance for SARS-CoV-2 is carried out by testing and monitoring wastewater for the genomic fragments of SARS-CoV-2, the virus that causes COVID-19. SARS-CoV-2 is present in the intestinal tract of many infected individuals, and the virus is then excreted into wastewater through feces. Research suggests that approximately half of people with COVID-19 shed the virus in their stool, whether they are symptomatic or not. Wastewater treatment plants can collect wastewater samples to be analyzed in a laboratory to look for the presence and amount of SARS-CoV-2. Increases or decreases in the amount of (concentration) SARS-CoV- 2 found in wastewater can help public health epidemiologists understand if COVID-19 cases in a sewershed are increasing or decreasing. Additional testing of the SARS-CoV-2 virus found in wastewater can also provide important information about circulating variants, including if a new variant is present in a community. Monitoring wastewater for COVID-19 variants, the quantity of SARS-CoV-2 virus, and changing trends provides public health with useful data to support COVID-19 preparedness and response. (return to top of page)ā
Wastewater surveillance for SARS-CoV-2 is carried out by testing and monitoring wastewater for the genomic fragments of SARS-CoV-2, the virus that causes COVID-19. SARS-CoV-2 is present in the intestinal tract of many infected individuals, and the virus is then excreted into wastewater through feces. Research suggests that approximately half of people with COVID-19 shed the virus in their stool, whether they are symptomatic or not. Wastewater treatment plants can collect wastewater samples to be analyzed in a laboratory to look for the presence and amount of SARS-CoV-2. Increases or decreases in the amount of (concentration) SARS-CoV- 2 found in wastewater can help public health epidemiologists understand if COVID-19 cases in a sewershed are increasing or decreasing. Additional testing of the SARS-CoV-2 virus found in wastewater can also provide important information about circulating variants, including if a new variant is present in a community.
Monitoring wastewater for COVID-19 variants, the quantity of SARS-CoV-2 virus, and changing trends provides public health with useful data to support COVID-19 preparedness and response.
Wastewater surveillance for SARS-CoV-2 is a supplemental tool used to help monitor the spread of COVID-19 within a community. Since wastewater surveillance does not rely on individual testing behavior or the use of specific tests (e.g., PCR) needed for a case to be recorded by public health, it can provide a more accurate reflection of disease activity in a community. In some cases, wastewater surveillance can help detect changing trends before increases can be seen in the number of reported cases, test positivity, or hospitalizations. Wastewater surveillance can also provide information on circulating SARS-CoV-2 variants in a community. This information can help local health departments, hospitals, and communities stay vigilant and prepare accordingly. (return to top of page)ā
Wastewater surveillance for SARS-CoV-2 is a supplemental tool used to help monitor the spread of COVID-19 within a community. Since wastewater surveillance does not rely on individual testing behavior or the use of specific tests (e.g., PCR) needed for a case to be recorded by public health, it can provide a more accurate reflection of disease activity in a community. In some cases, wastewater surveillance can help detect changing trends before increases can be seen in the number of reported cases, test positivity, or hospitalizations.
Wastewater surveillance can also provide information on circulating SARS-CoV-2 variants in a community. This information can help local health departments, hospitals, and communities stay vigilant and prepare accordingly.
āCollection methods may vary. However, trained professionals commonly use a device known as an autosampler to collect a composite wastewater sample over 24 hours, 1-3 times per week. Different laboratories may use different methods for sample processing and analysis. After the composite wastewater sample is collected and sent to a laboratory, SARS-CoV-2 genetic material (RNA) in wastewater samples is concentrated and isolated. Next, a molecular biology method called polymerase chain reaction (PCR) is used to detect and quantify SARS-CoV-2 RNA sequences.ā (return to top of page)ā
āCollection methods may vary. However, trained professionals commonly use a device known as an autosampler to collect a composite wastewater sample over 24 hours, 1-3 times per week. Different laboratories may use different methods for sample processing and analysis. After the composite wastewater sample is collected and sent to a laboratory, SARS-CoV-2 genetic material (RNA) in wastewater samples is concentrated and isolated. Next, a molecular biology method called polymerase chain reaction (PCR) is used to detect and quantify SARS-CoV-2 RNA sequences.ā
āāThere has not been evidence of infectious SARS-CoV-2 in effluent wastewater after processing of wastewater at a treatment plant. Wastewater treatment plants are designed to disinfect treated wastewater through multiple processes, including steps of either chlorination and/or ultraviolet light that are known to destroy the SARS-CoV-2 virus.
āThere is no current evidence to show increased risk of COVID-19 to workers at wastewater treatment plants.āā(return to top of page)ā
āThere is no current evidence to show increased risk of COVID-19 to workers at wastewater treatment plants.āā
In California, wastewater monitoring for SARS-CoV-2 is carried out by several groups. These include the California Department of Public Health (CDPH) California Surveillance of Wastewaters Program (Cal-SuWers). Other groups also monitor wastewater, with some contributing data to the California Wastewater Surveillance Network (CA WWS Network), managed by CDPH and with data used for state and local public health, and submitted to the Centers for Disease Control and Prevention (CDC) National Wastewater Surveillance System (NWSS). Groups participating in wastewater monitoring in California include: Local health departments Wastewater utilitiesā āā Academic researchers Commercial laboratories U.S. Centers for Disease Control and Prevention (CDC) National Wastewater Surveillance System (NWSS) via a contracted commercial laboratory California is a participating state in the CDC National Wastewater Surveillance System (NWSS). CDPH Cal- SuWers Program sites are monitored by the CDPH Drinking Water and Radiation Lab (DWRL), which conducts testing of samples from several counties across the state. (return to top of page)ā
In California, wastewater monitoring for SARS-CoV-2 is carried out by several groups. These include the California Department of Public Health (CDPH) California Surveillance of Wastewaters Program (Cal-SuWers). Other groups also monitor wastewater, with some contributing data to the California Wastewater Surveillance Network (CA WWS Network), managed by CDPH and with data used for state and local public health, and submitted to the Centers for Disease Control and Prevention (CDC) National Wastewater Surveillance System (NWSS).
Groups participating in wastewater monitoring in California include:
California is a participating state in the CDC National Wastewater Surveillance System (NWSS). CDPH Cal- SuWers Program sites are monitored by the CDPH Drinking Water and Radiation Lab (DWRL), which conducts testing of samples from several counties across the state.
Samples collected at CDPH Cal-SuWers Program locations are tested for infectious disease pathogens of public health concern including SARS-CoV-2, influenza, and mpox. Other programs that participate in the CA Wastewater Surveillance Network or the CDC NWSS program may test for other pathogens. (return to top of page)ā
Samples collected at CDPH Cal-SuWers Program locations are tested for infectious disease pathogens of public health concern including SARS-CoV-2, influenza, and mpox. Other programs that participate in the CA Wastewater Surveillance Network or the CDC NWSS program may test for other pathogens.
The CA Wastewater Surveillance (WWS) Network is able to cover more than 60% of the CA population with our combined network of contributing wastewater treatment plants (WWTPs). To learn more, visit the CDPH Wastewater Surveillance Network Dashboard. (return to top of page)ā
California has hundreds of active wastewater treatment plants, and due to resource constraints at the utility, laboratory, and public health levels, it is not currently feasible nor necessary to collect and test wastewater samples from all utilities in the state. The goal of the current wastewater surveillance program in California is to serve as a sentinel surveillance system with enough wastewater treatment plants participating from throughout the state to be representative of most populations and regions of the state to provide CDPH and local health jurisdictions with useful disease trends. (return to top of page)ā
California has hundreds of active wastewater treatment plants, and due to resource constraints at the utility, laboratory, and public health levels, it is not currently feasible nor necessary to collect and test wastewater samples from all utilities in the state. The goal of the current wastewater surveillance program in California is to serve as a sentinel surveillance system with enough wastewater treatment plants participating from throughout the state to be representative of most populations and regions of the state to provide CDPH and local health jurisdictions with useful disease trends.
āFor programs that are already conducting wastewater surveillance, please contact the CDPH Cal-SuWers Team at wws@cdph.ca.gov for more information on how to join the CA Wastewater Surveillance Network and CDC NWSS. (return to top of page)ā
āFor programs that are already conducting wastewater surveillance, please contact the CDPH Cal-SuWers Team at wws@cdph.ca.gov for more information on how to join the CA Wastewater Surveillance Network and CDC NWSS.
āTypically, the wastewater utility is responsible for collecting samples on-site, as they have the proper training, equipment, and access needed to collect raw wastewater samples safely. In some circumstances, partnership between local health departments and utilities can be formed to support the work of collecting and shipping samples to a testing lab.ā (return to top of page)ā
āTypically, the wastewater utility is responsible for collecting samples on-site, as they have the proper training, equipment, and access needed to collect raw wastewater samples safely. In some circumstances, partnership between local health departments and utilities can be formed to support the work of collecting and shipping samples to a testing lab.ā
āāFunding for each program that participates in the California Wastewater Surveillance network differs. The CDPH Cal-SuWers Program is funded through a CDC Epidemiology and Laboratory Capacity (ELC) grant. The cost of physically collecting the wastewater samples is currently being covered either by the participating sanitation district on a voluntary basis, or sometimes subsidized partially by the CDC grant. Lab testing for the CDPH Cal-SuWers programs is done at the CDPH Drinking Water and Radiation Laboratory, supported by these ELC funds.
āResults from the CDPH California Wastewater Surveillance Network can be found on the CDPH Surveillance of Wastewaters (Cal-SuWers) āNetworkā Dashboard.āā (return to top of page)āāā
āResults from the CDPH California Wastewater Surveillance Network can be found on the CDPH Surveillance of Wastewaters (Cal-SuWers) āNetworkā Dashboard.āā
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What is wastewater?
What is sewershed?ā
What is Wastewater-Based Epidemiology (WBE)?āāā
What is wastewater surveillance for SARS-CoV-2?
How are data from wastewater surveillance for SARS-CoV-2 being used to support COVID-19 public health preparedness and response?
āāHow do you measure SARS-CoV-2 in wastewater?
āāāāIs there evidence of infectious SARS-CoV-2 virus found in effluent, or processed wastewater?
Is there increased risk of COVID-19 to wastewater treatment plant workers?
Who does wastewater surveillance in California?ā
What pathogens does CDPH test for?
How large is the CA WWS Network?
Why is wastewater surveillance not carried out at every treatment plant in CA?
How can a wastewater utility get involved?
āāHow does the process of sample collection work?
How is this being paid for?
Where can I find the data?
CDC COVID Data Tracker Dashboardā
UC Berkeley Covid-WEB Dashboard
UC Davis public health projects: Healthy Davis Together and Healthy Yolo Together