NWT Wastewater Monitoring

Weekly wastewater samples are collected from participating NWT communities to test for respiratory viruses, including COVID-19, Influenza (flu), and Respiratory syncytial virus (RSV). 

The wastewater monitoring report is updated on Tuesdays. If there is a holiday, the report will be updated on the next business day.

View recent wastewater monitoring activity

Use the dropdown menu under "Select virus to see recent data" to toggle between results.

  • Weekly wastewater samples are collected from participating communities to test for respiratory viruses, including COVID-19, Influenza (flu), and Respiratory syncytial virus (RSV). 
  • The wastewater monitoring report is updated on Tuesdays. If there is a holiday, the report will be updated on the next business day.
  • Communities can choose to join the program at their convenience.

Use "Select community to see data" to select a participating community.

Toggle between "Show viral loads" or "Show detections" buttons.

Interpreting wastewater data

Virus detection

  • Each sample is tested to check for presence or absence of the virus. 
  • A detection means the virus was found in the sample.

Use caution when interpreting daily and short-term changes in the viral loads as wastewater signals can change from day-to-day.

More sustained increases or decreases in the viral loads are more reliable for seeing trends.

Virus concentration

  • The amount of virus in the sample, or viral load, helps indicate if infection levels are increasing or decreasing. 
  • A 7-day rolling average is used to smooth out short-term fluctuations in the data.

Viral load levels

  • The average viral load during the report is compared to the previous year's data and classified as high, moderate, low, or not detected.
  • Communities with insufficient data are noted. 

Data notes

  • Qualitative results (detect/no detect): Determined using the Cepheid GeneXpert system, a PCR test that detects virus genetic material in wastewater.
  • Quantitative results (viral load): Calculated by converting GeneXpert cycle threshold (ct) values to viral load values using the Canadian National Microbiology Lab's methods.

Citations

  1. Hizon N, Mejia E, Hannah E, Gregorchuck BSJ, Medina N, Becker MG, Mangat CS. GeneXpert Wastewater Surveillance. GitHub repository. https://github.com/Wastewater-Surveillance/GeneXpert_WW
  2. Daigle J, Racher K, Hazenberg J, Yeoman A, Hannah H, Duong D, Mohammed U, Spreitzer D, Gregorchuk BSJ, Head BM, Meyers AFA, Sandstrom PA, Nichani A, Brooks JI, Mulvey MR, Mangat CS, Becker MG. A Sensitive and Rapid Wastewater Test for SARS-COV-2 and Its Use for the Early Detection of a Cluster of Cases in a Remote Community. Applied and Environmental Microbiology. 2022. March 8th. doi: https://doi.org/10.1128/aem.01740-21

How wastewater monitoring works

People infected with respiratory viruses can shed pieces of the virus in their stool.

People infected with viruses like COVID-19, flu, or Respiratory syncytial virus (RSV) can shed pieces of the virus in their stool (poop), even if they feel fine.

The virus pieces travel from the toilet into the sewage system.

Wastewater samples are taken from the sewage system before treatment and sent for testing.

The lab tests the samples to check for the presence and amount of different viruses.

Data is used along with other information to spot trends and make decisions.

The Office of the Chief Public Health Officer and public health partners use this data, along with other information, to understand disease trends in NWT communities and make decisions to prevent the disease spread. 

NWT communities can choose to join the program at their convenience.

Benefits and limitations of wastewater monitoring

The benefits of wastewater virus monitoring are:

  • Helps identify if COVID-19, influenza A and B, and Respiratory syncytial virus (RSV) are present in a community.
  • Act as an early warning if the number of infections is increasing or decreasing.
  • Help public health officials make informed decisions, such as guidance on preventing infections, testing, and vaccination options.

The limitations of wastewater virus monitoring include:

  • Cannot prove that infections are absent in a community. Sometimes there may be too little virus in wastewater for a test to detect it.  
  • Does not estimate the number of infected individuals in a community. Wastewater provides trends but not specific numbers of people who are sick.
  • Cannot reliably compare trends between communities due to various factors affecting sample strength, like groundwater changes (e.g. snow melt), temperature, collection method, and other substances (e.g. cleaners and disinfectants).
Updated: Jul 07, 2026