SARS-CoV-2 Sewage Monitoring

COVID-19 information

For information regarding COVID-19 guidance and cases, see the Utah Department of Health COVID-19 information page.

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SARS-CoV-2 (the virus that causes COVID-19, hereafter referred to as the virus) is shed in feces by infected individuals. Virus concentrations in sewage can be measured by collecting a sample at the inlet of sewage treatment plants. This information provides a pooled indicator of the status and trends of COVID-19 infections in communities served by the treatment plant (the sewershed).

Utah DEQ is collecting samples at 42 sewage treatment plants in Utah, representing approximately 80% of the state’s population. The data from these samples provide a quantitative estimate of the average number of virus RNA gene copies entering the treatment plant and normalized to the number of people living in the sewershed. The data are updated regularly to provide additional information to public health partners regarding trends in virus prevalence in Utah’s communities.

Current Data

Important Note

On August 1, 2021, we moved all laboratory analyses associated with wastewater surveillance to the Utah Public Health Laboratory. There are a number of changes that could affect the end results displayed in this report, including sampling on different days, sample transportation times, RNA concentration/extraction methods, and the lab personnel running the analyses. It is extremely difficult to predict how these changes affect the results, though for at least some facilities the difference appears to be minimal. Results from some other facilities are now considerably higher. Ultimately, we expect the results post-change to be at least as accurate as previous data, if not more so.

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Background

SARS-CoV-2 viruses are shed in the feces of infected individuals. Virus concentrations in sewage can be measured by collecting a sample at the inlet of sewage treatment plants. This information provides a pooled indicator of the status and trends of COVID-19 infections in communities served by the treatment plant (the sewershed).Although the virus is unlikely to be viable or infectious at sewage treatment plants, more studies are needed to confirm this assumption. Sewage treatment systems do an excellent job of treating sewage and disinfecting viruses and other pathogens. Operators at these facilities follow appropriate steps to reduce risk of exposure to all pathogens in raw sewage.

Early in the pandemic a pilot investigation was conducted to evaluate whether or not the RNA of SARS-CoV-2 could be reliably quantified from sewage influent samples. Investigation results demonstrated that the number of gene copies could be reliably measured in the sewage of communities with known COVID-19 infections. It is currently not possible to reliably and accurately predict the number of infected individuals from sewage sample results, but the study results demonstrated higher RNA concentrations in communities with a higher density of infected patients. More importantly, the pilot study demonstrated that sewage results could be used to track trends in community infection rates, potentially providing an early warning of future outbreak events.

After seeing the pilot investigation results, Utah’s COVID-19 Unified Command requested that the wastewater epidemiology investigation be expanded statewide. It is not presently possible to measure SARS-CoV-2 RNA from every treatment plant in the state, so Utah’s DEQ and DOH selected facilities that could provide the most valuable information. Factors used to make these selections induced facility size, community susceptibility to new infections (i.e., large numbers of tourists) and the community Health Improvement Index.

Sampling Locations

Utah DEQ is working with wastewater treatment professionals to collect samples at 42 sewage treatment plants in Utah, representing approximately 80% of the state’s population. The map (“Current Data” tab) and table below shows the locations of the facilities along with the population served by each facility that will be sampled.

Facility NameCountyHealth DepartmentEstimated Population Served
Ash CreekWashingtonSouthwest15,000
Ashley ValleyUintahTri-county27,000
BlandingSan JuanSan Juan3,700
Brigham CityBox ElderBear River32,000
Cedar CityIronSouthwest29,000
Central Davis Sewer DistrictDavisDavis County58,000
Central Valley Water Reclamation FacilitySalt LakeSalt Lake County515,494
Central Weber Sewer Improvement DistrictWeberWeber – Morgan312,000
East Canyon Water Reclamation FacilitySummitSummit County23,304
FillmoreMillardCentral Utah2,400
GunnisonSanpeteCentral Utah4,000
Heber ValleyWasatchWasatch County24,000
HyrumCacheBear River9,095
Jordan Basin Water Reclamation FacilitySalt LakeSalt Lake County106,000
Logan CityCacheBear River94,005
MagnaSalt LakeSalt Lake County28,000
MoabGrand CountySoutheast9,896
MonaJuabCentral Utah3,000
MonticelloSan JuanSan Juan2,000
MoroniSanpeteCentral Utah1,500
North Davis Sewer DistrictDavisDavis County186,000
Orem CityUtahUtah County112,901
Payson CityUtahUtah County16,000
Price River Water Improvement DistrictCarbon CountySoutheast17,312
Provo CityUtahUtah County110,000
RichfieldSevierCentral Utah7,900
RooseveltTri-county12,000
Salt Lake CitySalt LakeSalt Lake County209,645
SantaquinUtahUtah9,300
Silver Creek Water Reclamation FacilitySummitSummit County10,000
South Davis SD NorthDavisDavis County69,000
South Davis SD SouthDavisDavis County35,000
South Valley Water Reclamation FacilitySalt LakeSalt Lake County206,000
Spanish ForkUtahUtah County41,000
SpringdaleWashingtonSouthwest2,900
SpringvilleUtahUtah County35,000
St. GeorgeWashingtonSouthwest106,000
Timpanogos Special Services DistrictUtahUtah County253,098
TooeleTooeleTooele21,000
TremontonBox ElderBear River12,451

Sample Frequency

Samples are being collected weekly at each of the 42 facilities. If results indicate a sharp increase, additional follow-up samples will be collected within the constraints of sample capacity. In most cases, results will be made available within 3 days of sampling on the data dashboard (“Current Data” tab).

Analytical Methods

Scientists at the University of Utah, Utah State University, and Brigham Young University developed a uniform method to measure the genetic material of the virus in sewage entering treatment plants. The laboratory method includes the same processes used for most clinical COVID-19 diagnoses. Virus concentrations were coupled with wastewater flow and service area populations to estimate viral concentrations in units of SARS-CoV-2 gene copies per person per day. This metric provides an indicator of changes in community infection rates in each treatment plant’s service area.

Resources for Partners

Partners

Publications

The Water Research Foundation hosted an international web conference on the detection of novel coronavirus using wastewater epidemiology. Experts discussed the promise and challenges of using this information to inform pandemic response.

Early preprints of several research papers have been released so that water and health professionals have access to the information while they undergo peer review. This includes a review of the state of knowledge of SARS-CoV-2 in wastewater and another review that calls for international coordination on these research efforts.

Several case studies provide early results for studies similar to the Utah pilot investigation and the potential for sewage monitoring as a leading indicator of COVID-19 infections including studies from: Massachusetts, Montana, Connecticut, France, the Netherlands, Australia, Spain, and Italy.

A group of Italian researchers have released the results of a study (339 KB) that affirms the conclusion of Utah’s pilot that treated wastewater poses little threat on the spread of novel coronavirus. A recent review paper reviewed all available literature on the topic and reached a similar conclusion.

Pilot Study

Sewershed Sampling Concept

View Our Pilot Study Results
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