SIOUX FALLS, S.D. (KELO) — Rates of COVID-19 are continuing to see a resurgence across the nation, including in South Dakota. While we often look to positive test numbers and hospitalizations as a way of estimating the extent of the disease in our communities, there is another way, and it starts with your toilet.

More accurately, this method of detection is done through testing wastewater, which comes from places such as sinks, showers and yes, toilets.

The CDC’s National Wastewater Surveillance System (NWSS) takes samples from wastewater treatment centers to test for the presence of a disease. But how exactly does this work?

According to the CDC, people infected with the COVID-19 virus can shed viral genetic material in their feces, which eventually ends up in the wastewater system. Most of this material tends to end up in a toilet, though material can also wind up in the system from showers, sinks and even outdoor drains.

While this method of detecting COVID-19 is useless when it comes to tracking individual cases, it can quantify the overall incidence of the virus in a large population, especially in areas where testing is underused or unavailable.

Jesse Neyens, Regulatory Compliance Manager for Sioux Falls Water Reclamation, explained via phone that samples of wastewater are collected as they enter the facility, where they are collected via a tube which pumps them into a sampler.

Neyens says these samples are collected throughout the day to ensure that a representative sample is achieved of all the wastewater coming into the facility.

The fist sampling date in Sioux Falls was June 6, 2022, and Neyens says they will be sending their 7th and 8th samples to the CDC this week, with two being sent each week.

Once collected, the city packages the samples in kits supplied by the CDC, which are then overnighted via FedEx.

In South Dakota, samples are collected in Sioux Falls, Rapid City, Yankton and Huron. Rapid City and Sioux Falls each had their first sampling dates in June, while Huron and Yankton’s came in May.

The CDC data on COVID-19 derived from the NWSS shows trends in the spread of the virus, as seen above in the charts from each city, which show concentration of the virus in the wastewater samples continuing to rise in Sioux Falls, Rapid City and Yankton.

Within South Dakota, 80-100% of all samples received showed a detectable amount of the virus.

Compared to where we have been for the past few years, South Dakota is doing better, implied Avera’s Dr. David Basel recently in an interview with Inside KELOLAND.