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Flooding can contaminate wells; private well owners encouraged to check their drinking water

Contact(s): Marty Nessman, DNR private water field supervisor, 608-267-2449;; Jake Sedivy, DNR private water supply specialist, 715-635-4027,; Jennifer Sereno, DNR communications, 608-770-8084,

July 12, 2016 at 4:26:22 pm

ASHLAND, Wis. -- Heavy rains such as those that swept through northern Wisconsin in the past several days can create conditions that affect private wells and drinking water.

"If you live in an area that was recently or is currently flooded, your private well may be in danger of contamination from pollutants carried in floodwaters," said Marty Nessman, DNR private water field supervisor with the Wisconsin Department of Natural Resources.

Well owners who observe flooding or changes in their water should assume their wells are contaminated and take the following steps:

Flood waters and runoff contain bacteria and other contaminants that can affect water supplies and cause water-borne illness. Wells located in pits, basements and low-lying areas are especially susceptible to contamination.

Even without obvious signs of flooding, a well can become contaminated. More recommendations for private well owners whose wells have been inundated are available on the DNR website.

"Disinfection and sampling are best done by a licensed well driller or pump installer," Nessman said. "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."

Private well owners are encouraged to test their wells annually for bacteria and nitrates, to check for problems and ensure the water is safe to drink. More information on bacteriological contamination of drinking water wells, along with lists of licensed well drillers, pump installer and labs certified to analyze water samples are available by searching the DNR website,, for the keyword "wells."

For individuals who receive their 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.

Additional information for those affected by the flooding can be found on DNR's website by searching "Coping with Flooding." The Wisconsin Department of Health Services also provides information and links to resources on its Flood Hazards and Recovery page: (exit DNR).

Last Revised: Tuesday, July 12, 2016

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