Tell Me More: Wastewater Surveillance

Public Health 101

10 Aug 2022

In this new series, Tell Me More, we discuss relevant health care topics, innovations, and trends in simple, easy to understand terms. We will share important information that you need to know and will provide insight into issues that matter to people in Ontario.

Wastewater surveillance

Since the onset of the COVID-19 pandemic, surveillance has been critical to tracking and preventing the spread of the SARS-CoV-2 virus. Throughout the past 2.5 years, as experts learned more about the virus, surveillance methods evolved to meet the needs of decision makers and people in Ontario. Wastewater surveillance (WWS) is a relatively novel method that can be used to track and monitor both SARS-CoV-2 and other viruses, including polio, measles, and hepatitis A, within communities.

Wastewater is used water collected by plumbing from households (e.g., toilets, laundry and sinks), commercial, industrial and institutional sources (e.g., process waste). In many locations, it includes seasonally varying levels of natural sources (e.g., storm water, and infiltration of groundwater). 

WWS involves samples taken from a specific community location such as a wastewater treatment plant or a high-risk facility such as a retirement home. Everyone in the relevant geographical area that contributes wastewater up to the sampling point (specific geographical area) is captured by the sample. The samples are then sent to laboratories across the province and analyzed for the presence of viral genetic fragments that help to understand the prevalence of disease in the sampled population (community) over time.

These data have been used by public health professionals to inform decision making. Since viral shedding in feces can occur early in the course of infection, and sampling wastewater does not depend on individual testing for infection, there is a potential for WWS to act as an early warning indicator for some diseases outbreaks. However, WWS for SARS-CoV-2 is new, with much more to learn about the science and practice of using the data.

Learn more about WWS in Public Health Ontario’s first Wastewater Surveillance of COVID-19 release.

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Published 10 Aug 2022