Rising waters had completely inundated the parking lot at Great River Park by Thursday, July 13. Shahrzad Rasekh / CT Mirror

Torrential rains caused widespread problems across the region this summer, ruining crops, washing out roads and flooding homes.

But there’s another, often unnoticed, consequence of all that rainwater pouring onto the ground — private wells are getting contaminated.

A UConn extension testing program established in September 2022 saw more wells contaminated with coliform bacteria this summer, according to Mike Dietz, an extension educator, and director of the Connecticut Institute of Water Resources.

Half of the water samples at the lab were positive for total coliform this summer, up from 30% in months prior, Dietz said. It’s a concern, because Connecticut’s thousands of private wells are less regulated than city water.

“Any public water supplier is required to test that water frequently, and have to meet all the EPA Safe Drinking Water Act requirements,” Dietz said. “Private well owners are only required to do that when the well goes in. The responsibility is on every person that owns that well.”

Coliform itself isn’t dangerous, but can indicate the presence of other bacteria from shallow groundwater leaking into residential wells, like E. coli, which negatively impacts health.

According to the state Department of Public Health, about one in four Connecticut residents rely on private wells. Currently, the EPA does not regulate private wells or provide recommended standards — and the state doesn’t require Connecticut homeowners to test their wells annually. Because of this, testing doesn’t happen enough.

Dietz said residents should test every one or two years, and the U.S. Environmental Protection Agency recommends testing if there is local flooding.

Wells with positive coliform samples are typically disinfected with bleach, a process which takes at least a week to complete. Then the lab tests the water again to ensure it’s safe. Health experts recommend bottled water for drinking and cooking until the issue is corrected.

This newer testing program at UConn doesn’t have a long-term record to compare data, Dietz said. The state DPH did not immediately respond to inquiries about how the rise in bacteria this year may have affected residents this year, or in past years with lots of rain.

As larger, more powerful storms are predicted to continue with climate change, excess rain poses more of a risk to water quality in rural areas.

“When we have a lot of rainfall — like we have this past summer — that excess rain gets down into the shallow groundwater, and can change the way that shallow groundwater moves and gets into the well itself,” Dietz said.

He added that his team is looking to continue the grant-funded program to expand the contaminants they can test for, and continue offering testing to residents at a low cost.

Information on certified labs and water testing is published online through local and state health departments.

This story was first published Nov. 10, 2023 by Connecticut Public.