How COVID-19 wastewater testing works in San Luis Obispo

Lab Analyst Tanner Duncan inspecting a sample
Posted at 5:39 PM, Dec 08, 2022
and last updated 2022-12-08 22:36:12-05

The City of San Luis Obispo tests weekly for COVID-19 in wastewater.

“This is everything that comes down the drain. It converges into one spot, and this is where we take our sample,” said Tanner Duncan, a Laboratory Analyst with the City of San Luis Obispo.

He takes samples from the city's wastewater facility every Tuesday.

He showed KSBY a large jug, 50 milliliters full, saying, “This is the product we have, so it's every 15 minutes over a 24-hour period.”

The city treats about 3 million gallons of wastewater from San Luis Obispo and Cal Poly every day.

Matthew Anderson, the Laboratory Manager for the City of SLO, explained, “With the beginning of COVID, the CDC identified two like genetic fingerprints to look for or to monitor COVID.”

SLO began a regional program in May of 2020 to monitor for COVID-19 and is a part of the CDC National Wastewater Surveillance Program which took off in 2021.

“We’re going to take this back to our to our lab and then we're going to pour off samples to send out to Cal Poly and one of our contract labs, Biobot, which is through the CDC,” Duncan added.

The lab analysts shake up the samples so they are homogenized, which means to combine them so they are the same.

The city's four full-time lab analysts also team up with two Cal Poly professors for specific projects like this one.

Dr. Pat Fidopiastis is a professor of Microbiology.

“I'll process those samples, I’ll extract viral RNA from them and quantify the amount of SARS-CoV-2 in the wastewater based on the amount of RNA that I detect,” he explained.

Anderson told KSBY that the program may soon be used to detect other viruses.

“The CDC program is beginning to open up," he said. "They are going to start looking for monkeypox in the near future.”

South County, Paso Robles, and Atascadero also do wastewater testing.