Now that official testing for COVID is much less common, testing sewage for the virus gives officials another way to track the disease.
In B.C., the wastewater testing program only expanded to the Interior last fall.
On Thursday, Global News took a tour of Kelowna, B.C.’s wastewater treatment facility to find out more about how that sampling is done and what health officials are learning from the results.
At the centre of Kelowna’s wastewater testing protocol is a small machine called a composite sampler.
It sits on top of a mini fridge in a hutch on the side of a building, and three days a week, it is hard at work collecting samples.
To make sure those samples are representative of what’s flowing through the plant, the machine automatically draws up a small amount of sewage every 15 minutes.
Each time it pulls up 50 mL of wastewater through a tube, from the flow passing by underground, and deposits into a sampling jug sitting in the mini fridge.
After 24 hours, all those 50 mL draws make up one composite sample the plant sends off to the B.C. Centre for Disease Control for analysis.
The sampling is done near the start of the treatment process just after large solids are screened out.
“So that is…. representative of what’s coming into the plant before any actual process has been done on it,” explained wastewater quality technician Jennifer Anderson.
Since last fall the wastewater sampling has helped Interior Health monitor the virus.
“There used to be testing that we did. Anybody with symptoms was able to go and get tested for COVID and now we have not done that anymore because the population is vaccinated, so using wastewater to understand how the virus is presenting in our communities is very helpful,” said Interior Health medical health officer Dr. Silvina Mema.
Mema said wastewater information should be looked at along with data about hospitalizations and test positivity rates to paint a picture of how COVID is behaving locally.
The viral load found in the Kelowna samples has fluctuated up and down and right now is on the increase but for Mema it’s too soon to call it a trend.
“We know that this is the respiratory season. It is not a surprise that there are respiratory viruses circulating…The question is what is going to be the trend after several weeks? Is this a little blip that is going to go down or is this the beginning of another trend going up,” Mema said.
Back at the treatment plant, the staff was careful to point out that before its discharged from the facility into Okanagan Lake the wastewater is treated with UV light which deactivates the COVID virus so it can no longer reproduce.
Right now, in the Interior, the wastewater testing is only being done in Kelowna, Kamloops and Penticton but the heath authority says it could be expanded to other communities.