Toronto Water

COVID-19: Wastewater Surveillance

Toronto Public Health (TPH) monitors COVID-19 activity in the community using a number of different data sources. With recent changes to the provincial testing strategy, TPH has been reviewing the use of additional sources of data to better understand the changes in COVID-19 activity. Wastewater surveillance involves testing for the virus in wastewater and looking at changes over time, helping us understand the true presence of COVID-19 in a community regardless of the testing strategy that is in place.

Ontario’s wastewater surveillance initiative is coordinated by the Ministry of the Environment, Conservation and Parks (MECP). Ryerson University and University of Toronto complete laboratory analyses on wastewater samples collected by the City of Toronto.             

This report is generated by MECP. This page is updated weekly on Wednesdays at 3 p.m. Technical notes for this report prepared by MECP are available .

While we aim to provide fully accessible content, there is no text alternative available for some of the content on this site. If you require alternate formats or need assistance understanding our maps, drawings, or any other content, please contact us at publichealth@toronto.ca.

Access the COVID-19 Wastewater Surveillance Report  (we recommend that you refresh the page to ensure that you are viewing the latest report).

As of December 31, 2021, the number of COVID-19 cases being reported is an underestimate of the true number of people with COVID-19 in Toronto due to provincial changes in testing eligibility 

The majority of Toronto’s wastewater is treated at four wastewater treatment plants located across the city: Ashbridges Bay (covering approximately 48% of Toronto’s population), Humber (24%), Highland Creek (17%), and North Toronto (8%). Peel’s Lakeview treatment plant covers the remaining approximately 3% of Toronto’s population.

Wastewater sampling occurs in the four wastewater treatment plants in Toronto 3-5 times per week. These four treatment plants have large sewersheds that cover approximately 97% of Toronto’s population. Data for Peel’s Lakeview treatment plant are not included in our dashboard.