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COVID-19 Wastewater Surveillance in Ontario

COVID-19 Wastewater Surveillance in Ontario

Wastewater surveillance is used by public health experts to track and monitor diseases, including COVID-19. This is done by testing community wastewater for the presence of SARS-CoV-2 from infected individuals —called the wastewater signal. This report presents the wastewater signal for Ontario, as well as its sub-regions.

Acknowledgement: The COVID-19 Wastewater Surveillance in Ontario report is based on the original work of the Ontario COVID-19 Science Advisory Table entitled, Wastewater Signals in Ontario, September 6, 2022.

This is a line graph of the estimated COVID-19 wastewater signal for Ontario. On the X axis is sample date. On the Y axis is standardized concentration of SARS-CoV-2 Gene Copies. Wastewater signals peaked in early January 2022 (wave 5), mid-April 2022 (wave 6), and mid- to late-July 2022 (wave 7). Wastewater signals began slowly increasing in mid-September.

This report is updated Thursdays at 4:30 p.m. ET (based on data extracted on Wednesdays)

For information on source data, citations, definitions, methods and more see our Technical Notes.

Download the data set (Excel format): 
COVID-19 Wastewater Signal Data.

To view an archived version of the report, see Archived Graphs.

This is a line graph of the estimated COVID-19 wastewater signal for the North region. On the X axis is sample date. On the Y axis is standardized concentration of SARS-CoV-2 Gene Copies. Wastewater signals peaked twice during wave 5, in early January 2022 and in early February 2022. Signals peaked again in mid-April 2022 (wave 6) and late July 2022 (wave 7). Wastewater signals began slowly increasing in mid-September 2022.

This is a line graph of the estimated COVID-19 wastewater signal for the North region. On the X axis is sample date. On the Y axis is standardized concentration of SARS-CoV-2 Gene Copies. Wastewater signals peaked twice during wave 5, in early January 2022 and in early February 2022. Signals peaked again in mid-April 2022 (wave 6) and late July 2022 (wave 7). Wastewater signals began slowly increasing in mid-September 2022.

This is a line graph of the estimated COVID-19 wastewater signal for the Eastern region. On the X axis is sample date. On the Y axis is standardized concentration of SARS-CoV-2 Gene Copies. Wastewater signals peaked in early January 2022 (wave 5), mid-April 2022 (wave 6), and late July 2022 (wave 7). Wastewater signals fluctuated through August and September 2022, then peaked again in early October 2022.

This is a line graph of the estimated COVID-19 wastewater signal for the Central East (excluding the GTA) region. On the X axis is sample date. On the Y axis is standardized concentration of SARS-CoV-2 Gene Copies. Estimates highlighted with a grey background, covering the most recent three weeks, are more likely to change. Wastewater signals peaked in April 2022, and September 2022. A smaller wastewater signal peak occurred in December 2022. Wastewater signals appear to be declining until mid-January.

This is a line graph of the estimated COVID-19 wastewater signal for the GTA region. On the X axis is sample date. On the Y axis is standardized concentration of SARS-CoV-2 Gene Copies. Wastewater signals peaked in early January 2022 (wave 5), in early April 2022 (wave 6), and mid-July 2022 (wave 7). Wastewater signals began increasing in mid-September.

This is a line graph of the estimated COVID-19 wastewater signal for the South West region. On the X axis is sample date. On the Y axis is standardized concentration of SARS-CoV-2 Gene Copies. Wastewater signals peaked in mid-January 2022 (wave 5), mid-April 2022 (wave 6). Wave 7 has seen three smaller peaks, in early August, early September, and late September 2022.

This is a line graph of the estimated COVID-19 wastewater signal for the Central West (excluding the GTA) region. On the X axis is sample date. On the Y axis is standardized concentration of SARS-CoV-2 Gene Copies. Wastewater signals peaked in mid-January 2022 (wave 5), mid-April 2022 (wave 6), and from mid- to late-July 2022 (wave 7). Wastewater signals have fluctuated since August 2022, with a small peak apparent peak in mid-September 2022 before declining until mid-October. Wastewater signal have been increasing since mid-October.

Grey Background: The dotted portion of the curves highlighted with a grey background should be interpreted with caution. These estimates have a higher likelihood of changing in future updates due to a combination of reasons, including but not limited to the analytical approach used, new data submissions for recent days or updates to previously reported data.

Ontario sub-regions: These refer to the following geographical groupings of public health units:

  • North West: Northwestern Health Unit and Thunder Bay District Health Unit.
  • North East: Algoma Public Health; North Bay Parry Sound District Health Unit; Porcupine Health Unit; Public Health Sudbury & Districts; and Timiskaming Health Unit.
  • Eastern: Eastern Ontario Health Unit; Hastings Prince Edward Public Health; Kingston, Frontenac and Lennox & Addington Public Health; Leeds, Grenville & Lanark District Public Health; Ottawa Public Health; and Renfrew County and District Health Unit.
  • Central East, excluding GTA: Haliburton, Kawartha, and Pine Ridge District Health Unit; Peterborough Public Health; and Simcoe Muskoka District Health Unit.
  • Greater Toronto Area (GTA): Durham Region Health Department; Halton Region Public Health; Peel Public Health; Toronto Public Health; and York Region Public Health
  • South West: Chatham-Kent Public Health; Grey Bruce Health Unit; Huron Perth Public Health; Lambton Public Health; Middlesex-London Health Unit; Southwestern Public Health; and Windsor-Essex County Health Unit.
  • Central West, excluding GTA: Brant County Health Unit; Haldimand-Norfolk Health Unit; City of Hamilton Public Health Services; Niagara Region Public Health; Region of Waterloo Public Health and Emergency Services; and Wellington-Dufferin-Guelph Public Health.

How to cite this page: Ontario Agency for Health Protection and Promotion (Public Health Ontario). COVID-19 wastewater surveillance in Ontario. Toronto, ON: King's Printer for Ontario; 2023.

Related Information

Updated 30 Nov 2023
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