Use this guidance to implement wastewater-based disease surveillance. Wastewater-based disease surveillance is a rapidly developing science, and CDC will continue to update guidance and information as it becomes available.
Targeted wastewater surveillance at facilities, institutions, and high-density critical infrastructure workplaces has been proposed as a complementary method for screening of COVID-19. To date, targeted wastewater surveillance efforts have primarily focused on institutions of higher education, correctional facilities, and workplaces like food processing facilities. Targeted surveillance entails sampling at locations in the wastewater network, such as manholes outside buildings, that receive wastewater inputs from only the targeted population.
Potential benefits of targeted wastewater surveillance
- Early warning of new cases in a targeted area.
- Focused monitoring of populations at higher risk for COVID-19.
- A cost and/or time-efficient screening approach— one sample comprises a pool of many individuals – that can complement individual testing.
Potential challenges of targeted wastewater surveillance
- To date, there are few data on the effectiveness of targeted wastewater surveillance to inform public health action or institutional operations.
- The minimum number of infected individuals that can be reliably detected through wastewater testing is not known.
- SARS-CoV-2 wastewater concentrations can be more variable when wastewater travel time is short and fecal load is low (e.g., sampling where waste leaves a building), potentially making it more difficult to understand COVID-19 trends in a targeted area.
- Environmental laboratory capacity may be limited due to competing demand for treatment plant level wastewater testing for community surveillance.
- Sampling a building wastewater stream may require modifications for waste stream access.
- Non-human industrial or facility waste outputs may interfere with detection of SARS-CoV-2 in wastewater.
Integration with case surveillance
Targeted wastewater surveillance should complement, but not replace, case surveillance approaches in accordance with state, tribal, local, and territorial (STLT) laws and regulations. Include STLT health departments when developing targeted wastewater surveillance strategies. Prior to implementing targeted surveillance, review CDC guidance on community-level wastewater surveillance, which includes considerations for developing a sampling strategy, sample testing, data analytics, and public health interpretation. If you are including building-level sampling in your targeted surveillance plans, CDC recommends collecting accompanying samples at the community level to interpret building-level viral signals. Do not use the lack of SARS-CoV-2 detection in wastewater alone to justify relaxing community mitigation measures.
Institutions of higher education and schools with on-campus housing may be served by their own wastewater treatment plant. These plants typically receive waste from residential, non-residential, and laboratory facilities, and in some cases, from on-campus hospitals.
When considering implementing wastewater surveillance on campus, institutions of higher education should work with campus health services and refer to the Considerations for Institutions of Higher Education and Interim Guidance for Case Investigation and Contact Tracing in Institutions of Higher Education (IHEs) to develop campus COVID-19 surveillance and mitigation strategies. Determine the implications of detecting SARS-CoV-2 in campus wastewater and resulting public health actions prior to beginning sampling. In particular, IHEs should consider how detection of SARS-CoV-2 in wastewater will affect campus mitigation strategies and case surveillance.
Residential occupants in correctional facilities contribute regularly to the waste stream. As a result, wastewater surveillance data may provide a representative indicator of the presence of COVID-19 case patients within the residential population of a facility.
Wastewater surveillance data can complement and be paired with routine clinical surveillance for SARS-CoV-2 of persons who are incarcerated and staff at correctional facilities. When considering implementing wastewater surveillance, correctional facilities should refer to Interim Guidance on Management of Coronavirus Disease 2019 (COVID-19) in Correctional and Detention Facilities to develop COVID-19 surveillance and mitigation strategies for their facility.
High-density critical infrastructure workplaces, such as food processing facilities, may be difficult to monitor using wastewater surveillance because employees are at the facility only during their work-shift and may contribute little to the waste stream relative to industrial waste (e.g., food production wastewater). Such industrial waste products may also complicate SARS-CoV-2 detection. Testing wastewater from the communities where the workers primarily live may be better than sampling from workplaces.
When considering implementing wastewater surveillance, high-density critical infrastructure workplaces should refer to guidance on COVID-19 Critical Infrastructure Sector Response Planning and Testing Strategy for Coronavirus (COVID-19) in High-Density Critical Infrastructure Workplaces after a COVID-19 Case Is Identified to develop COVID-19 surveillance and mitigation strategies for their facility.