Experts say seasonal changes can introduce bacteria into groundwater
Spring conditions can raise contamination risks for private wells in southwestern Ontario, experts say.
When snow melts and heavy rain hits, groundwater can shift. That can carry bacteria and other contaminants into wells.
“In the spring, we get snowmelt and flooding… and that can bring new contaminants into the groundwater,” said Claire Robinson, a professor of civil and environmental engineering and Canada Research Chair in Water Quality at Western University.
The Middlesex-London Health Unit logo is shown. (Middlesex-London Health Unit
Robinson said wells can pick up bacteria, viruses and parasites from agricultural runoff, along with naturally occurring metals.
Some of those contaminants aren’t easy to spot.
She said the impact depends on what’s in the water. Bacteria and parasites can make people sick quickly, while long-term exposure to things like nitrates or metals can lead to more serious problems.
Robinson pointed to the Walkerton water crisis in 2000 as an example of how bad contamination can get if it isn’t caught early.
Health officials say regular testing is the best way to stay ahead of it.
Andrew Powell, manager of Safe Water, Tobacco Enforcement and Vector-Borne Disease at the Middlesex-London Health Unit, said private well water in the region is generally safe. Testing helps confirm that.
“What we try to promote is people’s awareness of the free water testing services that are available… to confirm its safety and ensure the health of residents,” Powell said.
He said bacteria getting into wells is the most common issue locally. It’s often linked to damage, nearby construction or changes in groundwater.
Sometimes, Powell said, positive results come down to how samples are taken. That’s why the health unit gives instructions.
Free testing kits are available across London and Middlesex County. Residents can collect a sample from a tap and drop it off at a lab. Results usually come back within a few days.
Robinson said experts recommend testing for bacteria such as E. coli several times a year — especially during spring conditions — along with yearly checks for nitrates and metals.
“There is probably a subset of homeowners who under-test their wells,” Robinson said.
Powell said anyone who gets an unsafe result should contact the health unit to figure out what’s going on.
It could be a sampling issue. It could be the well itself.
If the issue continues, he said, a professional inspection may be needed.
