Wastewater Epidemiology & Surveillance Program

Wastewater surveillance is a method to monitor for pathogens within a community. It involves the systematic sampling, processing, and analysis of wastewater to detect the genetic material of targeted pathogens. The interpretation of wastewater data may be a valuable complement to more traditional public health tools, such as clinical testing and syndromic surveillance, to inform public health practice. Wastewater surveillance may also be referred as wastewater-based disease monitoring.

Wastewater surveillance is an effective tool to track pathogens within a community and has been in practice for decades (for example, to facilitate the eradication of polio). During the COVID-19 pandemic, wastewater surveillance was used to track SARS-CoV-2 levels within communities, allowing public health officials to alert community members of increased viral levels and to recommend health-protecting behaviors (such as social distancing, masking, etc.). Wastewater surveillance is more effective than relying on reported cases alone, as wastewater sampling may detect pathogens within the community regardless of individual symptom status (symptomatic or asymptomatic).

Genetic material of pathogens may be shed by infected individuals within their respiratory secretions or feces regardless of symptom status (symptomatic or asymptomatic). Wastewater, also referred to as sewage, includes water from household or building use (such as toilets, showers, or sinks) that contain human respiratory secretions or fecal waste, as well as water from non-household sources (such as rain or industrial use), allowing for the detection of pathogen genetic material in wastewater

Wastewater from a sewershed (the community area served by a wastewater collection system) is collected as it flows into a treatment plant. The samples are sent to public health laboratories for pathogen testing, including quantification and genetic sequencing of detected pathogens. DSHS reports testing results to participating sites and the public weekly.

Wastewater surveillance, when combined with traditional public health surveillance systems, may inform public health prevention and intervention measures and allow communities to lessen the health and socioeconomic costs of infectious disease outbreaks. Because wastewater surveillance does not require community members to seek testing from a health care provider and can be representative of large portions of a community, it gives public health officials a way to detect and characterize infection trends in a non-invasive, timely, and cost-effective way.

Communities – whether cities, neighborhoods, or facilities – that participate in wastewater surveillance use the data in several ways.

Examples of how communities have used wastewater trends include:

• Confirm clinical testing data – Are infections in the community decreasing or increasing? Or is clinical testing not capturing all infections? Is additional clinical testing required in some communities?
• Alert public health earlier – Studies have shown that wastewater data can indicate some disease trends up to two to fourteen days before clinical testing data. This provides public health officials important time to respond to increasing pathogen transmission.
• Indicate presence of pathogen variants of concern - Wastewater may be the first indication that a pathogen variant of concern is present in a community. For example, wastewater samples have tested positive for Omicron (a variant of SARS-CoV-2, which is the pathogen that causes COVID-19) before it appeared in nasal swabs.
• Shape public health policies – Are public health measures in place helping to reduce community transmission?
• Direct resources where they are needed – Which communities have the highest levels of transmission, and how can resources be better allocated to reduce disease spread?

Wastewater surveillance is conducted at participating wastewater treatment plants in municipalities that expressed interest in utilizing wastewater monitoring data to inform public health practice within their communities. If your municipality is interested in participating in wastewater surveillance, you may contact wastewaterepi@dshs.texas.gov for additional information.

DSHS partners with local health departments and water utilities to collect and interpret high-quality, community-level wastewater monitoring data that helps protect public health in Texas.