Another tool in the fight against COVID-19 could be what goes down your toilet.

The City and County of Honolulu says it’s using wastewater surveillence to see if there are spikes in COVID-19 that are unaccounted for by more traditional testing.

COVID-19 can be found in fecal matter, which is why the Department of Environmental Services began collecting samples through wastewater two weeks ago. The samples are then sent to a lab called Biobot Analytics in Massachusetts.

“The technology that this came out of was actually for opiods to see how much opiods were being used in cities and they were testing wastewater to find out what was the prevalence,” Honolulu Chief Resilience Officer Josh Stanbro said.

That technology was then transferred to find COVID-19. Honolulu is now one of 170 wastewater facilities in 37 states using Biobot.

If you’re worried about privacy, the results won’t be able to pinpoint where the disease is. It tracks larger trends and how prevalent the virus is among the population, which is data not currently widespread enough to find through more common means of COVID-19 testing.