As schools gear up for reopening, whether it’s a hybrid or remote model to start, every city and town is keeping a close eye on the number of COVID-19 cases in their community as a factor in deciding whether to reopen school buildings.

But there’s another approach worth considering: poop — more tastefully known as wastewater. Inside Biobot Analytics’ lab in Cambridge, scientists are giving it a close look.

“Everyone contributes to the wastewater whether they are symptomatic or asymptomatic, whether they have access to molecular tests or not, so it’s a much more egalitarian or unbiased way to survey levels of virus in the greater community,” explained Kyle McElroy, a research scientist at Biobot.

Basically, not everyone gets tested for COVID-19, but everyone poops. Wastewater from 43 communities ends up at the Deer Island treatment plant in Boston Harbor. Over the last several months, the Massachusetts Water Resources Authority has been sending samples three times a week to Biobot Analytics to test for COVID-19 levels.

“What we measure today predicts what happens in the community in four to seven days. So it’s sort of like looking into a crystal ball in the shape of a toilet,” McElroy said.

Wastewater epidemiology is not new but it’s having a moment. In late August, the University of Arizona traced COVID-19 samples in wastewater back to a dorm. After testing all the residents, two asymptomatic students tested positive for COVID-19 and were subsequently removed, arguably preventing a widespread outbreak.

Research has shown that people infected with COVID-19 start to spread the virus before they experience symptoms. That's why Cambridge is using Biobot’s wastewater data as one of three factors in reopening its schools for in-person learning.

Cambridge Mayor Sumbul Siddiqui, who also chairs the school committee, said connecting with the city’s community of scientists and public health experts was a natural fit.

“There hasn’t been much guidance from the state, and we knew that and we urged our superintendent to rely on the experts who are doing this work and not to wait for the state," he said. "It’s about following the data, following the science.”

The Massachusetts Department of Elementary and Secondary Education didn’t respond to a GBH News request for comment on whether the agency is considering wastewater epidemiology as part of its guidance for reopening. But as testing continues to have its issues, this may be poop’s moment to shine.