Once, it was being checked for the coronavirus.

Now samples are being taken twice a week to track another public health crisis: opioids

North of San Francisco, Marin County's drug overdose deaths are on a steady rise, from 30 in 2018 to 65 in 2021, according to its health department.

Now, public health officer Dr Matt Willis says they lose someone from overdoses every five days.

And he says sinks, showers and toilets may be one solution to tackle the crisis.

"The risk of dying from an overdose in Marin County was ten times higher than from dying from COVID-19 for anyone under age 60 last year. And so we really think it's important for us to develop the same kind of surveillance methods, the same kind of intelligence we had applied to the COVID-19 pandemic, to this new crisis of overdoses."

The county began a pilot program in February to test for fentanyl, methamphetamines, cocaine and more.

It's the same method and same Massachusetts-based lab partners from the coronavirus testing program, so the pilot's infrastructure is largely in place.

"One of the great things we learned about COVID-19 is that when it's excreted into the wastewater, we're actually able to use concentrations of the virus in the wastewater to determine how much virus is circulating in the community. And we want to know the same thing about what is one of the most important threats to health in our community, which is substances that are causing overdoses."

The data still needs to be validated, but authorities hope the pilot program will find out whether this type of monitoring can help with prevention and intervention efforts.

For example, if there's an abundance of opioids present in the samples, they could boost the distribution of the medication that saves lives from an opioid overdose.