DALLAS (CBSDFW.COM) – Some cities around the country are testing samples of raw sewage to look for COVID-19 faster than human lab testing can.

So far, no North Texas cities are doing this.

Studies are finding that what goes down everyone’s toilet could hold vital clues to detecting and tracking outbreaks of COVID-19, days or even weeks before patients show up in emergency rooms.

The sewage, also called wastewater, contains bacteria and viruses like COVID-19 cities are now examining as a surveillance system to detect outbreaks.

In Utah a few weeks ago, a high amount of COVID-19 was detected in sewage samples about a week before nearly 300 cases of the virus were confirmed at a meat processing plant.

Jenna Covington, Assistant Deputy of Wastewater with the North Texas Municipal Water District which treats the sewage of 24 DFW area cities, participated in a national research study which she says showed mixed results.

“This is a very new and evolving technology that, the researchers are working with,” said Covington. “And so absolutely there’s potential as we look into the future to be able to really use this information to support decision-making. But what we have found in the results that we’ve received is that there’s significant variability.”

Wastewater testing has been around for decades and was first used to detect outbreaks of polio.