CoronavirusNewsScienceThe SouthSider

Lab tests of sewer water help search for COVID-19

In a lab at the University of Missouri-Columbia, vials of chilled raw sewage from treatment plants throughout the state will soon reveal how serious a dread disease is in locales throughout the state.

In efforts to keep track of COVID-19 in Missouri, a branch of the Missouri Department of Health and Senior Services has the lab test 166 samples from132 locations throughout the state each week.  Among them are samples from all seven sewage treatment plants of the Metropolitan St. Louis Sewer District.

“We just provide the samples to the state, who then interprets them. They release the data to the county and city health departments,” said Sean Hadley, a spokesman for the MSD.

“Significant increases in viral load have been shown to predict increases in known human cases about a week in advance,” Jeff Wenzel, chief of the Bureau of Environmental Epidemiology of the Missouri Department of Health and Senior Service’s Division of Community and Public Health, said in an email. “This provides the department and local agencies some early indication of increases in cases.  We have also been able to see indications of variants of concern in many communities prior to human testing.”

The Missouri Department of Health and Senior Services started the testing for COVID-19 in sewage water in May 2020. 

Five staffers of the Health and Senior Services Department spend much of their time on the sewershed testing. In addition, workers for the state Department of Natural Resources spend time with wastewater operators to ensure the sampling goes smoothly. That’s besides the actual testing by the University of Missouri-Columbia.

“We started seeing some level of COVID-19 as soon as we started testing.  As COVID-19 cases were already known at that time, those results were expected,” Wenzel said in an email.

At each location, workers collect samples before the treatment process. A machine collects composite samples once an hour over a 24-hour period. Then it’s put into three small tubes, each equivalent to a twentieth of a liter.

Then workers pack the samples in a cooler on ice and send them overnight to the lab in Columbia.  There, they go through different kinds of tests.

One tests the water as humans are tested, to determine how much of the virus is present, to look at trends. That’s been going on since May of last year.  Another determines whether a variant is present. 

Missouri doesn’t test for other diseases, but it might, Wenzel said.  We have done some initial testing to find out if we could see other diseases, and we can.  However, we do not know if sewershed testing has a similar predictive ability for these other disease or not.  It is something we would like to research further.”

The health and senior services department heard testing such as that was going on in the Netherlands. Then the Missouri Department of Natural Resources contacted individual sewer systems and arranged for them to send in the samples. 

The first of the highly contagious Delta variant started showing up in May. The most recent tests indicated that the variant was present in all locations. 

Usually, increases in the number of cases come about six days after it shows up in the samples, Wenzel said.

Jim Merkel Born and raised in the St. Louis area, Jim Merkel covered communities throughout the area from 1991 to 2013 for the old Suburban Journals of Greater St. Louis. He is the author of five books about the Gateway City published by Reedy Press. The latest is Growing Up St. Louis: Looking Back Through the Decades. He and his wife, Lorraine, live in the Bevo Mill neighborhood of south St. Louis with Miss Jenny the Cat. For more about Jim, visit

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