Dept. of Natural Resources: Recent rainfall, flooding may contaminate wells

CONTACT: Liesa Lehmann, DNR private water section chief, 608-267-7649,; Marty Nessman, DNR private water supply field supervisor, 608-267-2449,

Well owners encouraged to be vigilant

MADISON — Recent heavy rainfall, mixed with warming temperatures, snow melt and lingering frozen ground can create conditions that may affect private wells and drinking water across central and southern Wisconsin.

“Our recent rain, mixed precipitation and local flooding throughout the state is a reminder that changing spring weather can lead to well contamination,” said Liesa Lehmann, Department of Natural Resources Private Water Section chief. “At this time of year we encourage well owners to watch for signs of flooding and note any change in the color, smell or taste of their drinking water.”

Lehmann said wwners who see flood waters very near or over their wells should assume their drinking water may be contaminated and to take the following steps:

stop drinking the water and find another safe source;
once the waters recede, make sure the well is properly disinfected; and
before drinking the water again, sample the well to assure the water is safe.
Flood waters and rain runoff may contain bacteria and other contaminants that can affect water supplies and cause illness. Wells located in pits, basements and low-lying areas are especially susceptible to contamination.

“Disinfection and sampling is best done by a licensed well driller or pump installer” says Lehmann. Any water supply system that has been submerged by flood waters should be pumped out once the floodwater recedes, then thoroughly disinfected and tested to determine that the water is safe.

To ensure safe drinking water, well owners are encouraged to learn whether they have a properly constructed well and test it annually for bacteria. More information on bacterial contamination of drinking water wells, along with lists of licensed well drillers, pump installers and labs certified to analyze water samples can be found by searching the DNR website,, for keyword “wells.”

For individuals who receive drinking water from a public water supply, these systems are designed and operated to keep out contaminants. If you have concerns about the safety of your community’s drinking water, contact your public water supplier.