Heavy snowfalls this winter created the likelihood for flooding in certain parts of the state. The Minnesota Department of Health (MDH) is advising well owners that private water wells contaminated with flood water can pose a health risk. MDH recommends that well owners take precautions before possible flooding and take corrective actions if their well is flooded.
MDH recommends 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 cap
or cover on your well - temporarily replacing the regular vented well cap
or seal.
- If you don't have time to have a professional install a watertight
cap, 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. Do not use duct tape - it
won't hold under flooding conditions.
- Be prepared to have your well disinfected and tested after the
flood waters recede, if your well does become flooded. Installing a
water-tight cap or securing a plastic covering won't eliminate the need
for disinfection and testing, but it will help keep debris and sediment
out of the well, and make the post-flood clean-up go more smoothly.
- If flood waters cover the top of the water well casing, water from
your well should not be used for drinking or cooking until the floodwater
recedes and the well is disinfected and tested. Until then, use bottled
water for drinking, cooking, or brushing your teeth.
After the flood waters recede, if the water reached your well casing, assume your well is contaminated. You should take the following steps to make sure your well is safe:
- If your well was not protected prior to the flooding, have a
professional well driller clean out any sediment and debris. Using your
well pump to flush out the well could ruin the pump. A directory of
licensed well contractors is available on the MDH website at: www.health.state.mn.us/divs/eh/wells/lwc/.
- Disinfect the well yourself or have a well contractor disinfect
the well. Disinfect the well using a chlorine solution before having it
tested. Detailed instructions are available at: www.health.state.mn.us/divs/eh/wells/waterquality/disinfection.html.
- After disinfecting the well and pumping out the chlorine solution,
contact a MDH-certified testing laboratory about submitting a water
sample. Tell the lab staff you need to have your well tested for coliform
bacteria – or simply "bacteria." They will tell you what you
need to do, and provide a bottle for the sample. To find a lab, contact
your local health department, or go to: https://apps.health.state.mn.us/eldo/public/accreditedlabs/labsearch.seam.
- Be prepared to repeat the disinfection and testing process several
times, if necessary, to ensure that your well is free of bacterial
contamination.
- Don't drink water from your well until the lab has informed you
that it is safe and free of bacterial contamination.
If flood water came within 50 feet of your well - but did not reach the wellhead:
- You may still want to have your water tested as a precaution.
- You should not need to disinfect your well before having it
tested.
If flood water did not come within 50 feet of your well, you do not need to do anything and your well should be fine.
For more information about well safety and protecting your health during a flood, visit www.health.state.mn.us/divs/eh/emergency/natural/floods/.
