Protect Your Wells From Flooding

Protecting your well from flood waters now can reduce your work later.

“If you live in a flood-prone area, you or a licensed well-drilling contractor can determine if your well is sited and constructed so that it is protected,” says Roxanne Johnson, North Dakota State University Extension Service water quality associate. “If your well is more than 50 years old or less than 50 feet deep, it likely could be contaminated by flood waters.”

Here are some steps to take if you think your well is in danger of being flooded:

Store a supply of water before taking your well out of service.

Turn off the electrical power to your well and seal it by installing a watertight cap or cover. This watertight seal replaces the regular vented cap for the duration of the flood.

If you don’t have time to install a watertight cap, clean the outside of the well casing and cover the top of the well with a heavy-duty trash bag or other heavy plastic sheeting. Secure the plastic covering with electrical or strapping tape or some other type of waterproof taping material. Don’t use duct tape because it is not waterproof.

Do not store oil, gasoline, solvents, animal wastes and chemicals such as pesticides and fertilizers within 100 feet of the well to reduce the chance of contaminants entering your well and contaminating the groundwater.

Place free-standing fuel tanks where flooding will not affect them, or anchor the tanks to keep them from moving with the flood waters. Identify large tanks with your name and address so they can be returned if they become displaced. Store drums and smaller containers in a fenced area, cabinet or storeroom.

Determine whether underground tanks are engineered to keep them from floating out of the ground if the contents are lighter than water.

“Once the water has receded, you need to determine if water reached the well casing,” Johnson says. “If it did, you should assume that your well was contaminated and take measures to make sure your well is safe.”

The first step is to determine if sediment or mud got into the well. If it did, contact a well driller to clean out the well.

Next, you will need to disinfect your well. You can do this yourself or have the well contractor do it following the cleaning operation. Information on this process is available at

After the well is disinfected, you will need to have a certified laboratory test your water for coliform bacteria.

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