MDH warns private well owners of flood risks, urges preventative action

With flood levels expected to crest in many Minnesota communities this week, health officials are warning private well owners of the risks posed by floodwaters.

The Minnesota Department of Health (MDH) says it’s important for anyone with a private well to take preventative action if they may be impacted by floodwaters so they reduce the chances of their drinking water becoming contaminated.

Contaminated wells pose a health risk and the impact is usually less visible than other flood damage, officials say.

With that in mind, MDH is urging private well owners to:

  • If in a flood-prone area: Consider contacting a licensed well contractor to check the well and make any repairs or changes to protect it from flood. Changes could include fixing cracked casing, extending the casing above the expected flood level or temporarily replacing the vented cap with a watertight cap.
  • If the well may become flooded: Store a supply of clean water that will last for a few days, then shut off power to the well pump to avoid having floodwater pumped into the home or plumbing system. Wells can also be covered with a heavy plastic bag or sheeting to help reduce contamination.
  • If floodwater comes within 50 feet of the well but doesn’t reach it: Have the well water tested for coliform bacteria as a precaution and disinfect it if the test comes back positive.
  • If floodwater reaches the well: Assume the well is contaminated and don’t use any water from the well for drinking, cooking or brushing teeth until floodwaters recede. In this event, MDH says it’s also important to take the following steps:
    • Avoid electrical shock. Don’t approach the well until it’s completely disconnected from its power source.
    • If floodwater covered the well or may have entered it directly: Have a licensed well contractor inspect the well, clean out sediment or debris and disinfect it. Using a well pump to remove sediment or debris could ruin the pump. A directory of licensed well contractors is available at: Licensed Well and Boring Contractor Directory.
    • If floodwater reached the well but didn’t enter it: Have a licensed well contractor disinfect the well or complete the disinfection yourself. Detailed instructions are available at Disinfecting Flooded Private Water Wells.
    • After the well is disinfected and the chlorine solution is pumped out, contact the county health department or a lab accredited by MDH to set up a well testing for coliform bacteria. They will provide sampling instructions. Accredited Labs in Minnesota Accepting Samples from Private Well Owners (PDF).