Caution urged for wells in flooded areas

State health officials are warning that contaminated private water wells pose a major public concern during the flooding now threatening various parts of Minnesota.

Although simply coming in contact with flood water shouldn’t pose a significant infectious disease risk, contamination of drinking water is a different matter, according to John Linc Stine, Assistant Commissioner at the Minnesota Department of Health. Well owners are advised to take steps to deal with potential contamination problems, both before and after a flood.

“If flood waters cover the top of your well casing, your well will have to be pumped out, disinfected and tested before you can start using the water again,” Stine said. “If you anticipate flooding, you may want to take precautions to protect your well. That can make the clean-up process easier.”

City water systems are unlikely to become contaminated, Stine noted, because city wells are generally protected from flooding.

Detailed instructions for disinfecting and testing private wells is available on the MDH Web site and from the district offices with well management units in Bemidji, Duluth, Fergus Falls, Marshall, Rochester, St. Cloud and the metro area.

Well owners who expect flooding may want to seal the top of their wells before the flooding starts to keep sediment and debris out of the well. That won’t eliminate the need for disinfection and testing, but it can make the post-flood clean-up go more smoothly.
MDH recommends that well owners take the following steps if they think their well may become flooded:

  • Store a supply of clean water before taking your well out of service.
  • Disconnect the power supply for your well. If you need help, consult with a licensed well contractor or pump installer.
  • If you have time, have a well contractor install a water-tight seal on your well – replacing the regular vented well cap or seal.
  • If you don’t have time to have a professional install a watertight seal, clean off the outside of the well casing and cover the top of the well with a heavy-duty trash bag or some other form of heavy plastic sheeting. Secure the plastic covering with electrical tape or some other type of waterproof tape or strapping material.

More information on well management during flooding can be found on the MDH Web site at The Web site also contains other information on protecting your health before, during and after floods, including information on home clean-up.

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