RICHMOND, Va. (WRIC) — As the latest wave of the COVID-19 pandemic subsides, doctors at the Virginia Department of Health (VDH) say good news is coming from an unexpected place: the sewers.

Dr. Rekha Singh manages the Wastewater Surveillance Program at the VDH, which monitors the amount of COVID-19 found in water treatment facilities.

Recently, she says the signs have been pretty good, adding, “Based on our recent data, I would say it’s consistently decreasing.”

The testing works because humans expel “viral particles of SARS-COVID-2” — among other things — when they go to the restroom.

Unlike traditional testing, which can be expensive and require access to medical facilities, wastewater surveillance lets health authorities get a “snapshot” of COVID levels.

“This means a single sample can give an estimate of infection across the whole community,” Singh said.

There are 25 facilities located in water treatment plants across the Commonwealth that perform weekly tests to determine “the trends of the virus in communities.”

Another advantage, especially with mild strains of COVID like the omicron variant, is that the tests reflect both symptomatic and asymptomatic cases, which might otherwise go unnoticed in traditional COVID case counts.

“This type of monitoring is very useful, and it can fill the gap when testing is very limited,” said Singh.

Nineteen of the state’s facilities recently reported that their viral loads were below detection — meaning there were very few cases in the community — but the program still plays an important role, according to Singh.

“It can provide early warning by detecting the disease ahead of clinical testing,” the doctor said.

The uptick will show up in wastewater about a week before formal case counts rise – so if you want to know when cases are set to rise, just watch your waste.