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Preparing Wells and Septic Systems for a Flood

Media contact: Allison Sandve, U of M Extension, ajsandve@umn.edu, (612) 626-4077

ST. PAUL, Minn. (4/8/2013) —If you live in an area with flooding in your spring forecast, you will want to make sure your wells and septic systems are as prepared as possible. Portions of the region on both the North Dakota and Minnesota sides of the river are at more than 80 percent risk of major flooding, according to Mark Seeley, University of Minnesota Extension climatologist.

Extension experts in well and septic systems suggest the following steps to prepare for a flood:

For wells

  • Make sure the well has a tight fitting waterproof cap.
  • Wrap the cap and well casing with durable sheet plastic and duct tape, then place sand bags around the wells.
  • Ensure that backflow prevention valves are in place.
  • Turn the electricity off to your well pump just prior to the flood. Do not turn the electricity back on until the flood waters recede.
  • Make sure the surface seal outside the casing is in good shape.
  • Ensure that the land surrounding the well is sloped away.
  • If the well is not used during the flood, plug the vent holes. Remember to unplug the vent holes after threat of flood is passed.
  • If flood waters inundate your well head, you will need to test the water to make sure it's safe even if you have followed the pre-flood recommendations. Find out in advance how and where you can get a well water text after the flood waters recede.
  • Buy or fill sanitized containers with water. Store them where they won't be flooded, so you have some safe drinking water until your well can be put back in service.


For septic systems

If you are in a location defined as a floodplain, there are a few things that can be done well in advance of any flooding. These include:
  • Maintain a healthy system. A well-maintained septic system is better able to withstand the stresses of flooding. Helpful operation and maintenance information can be found at septic.umn.edu/owners.
  • Ensure all access points to the system (maintenance holes and inspection ports) are properly covered to prevent the flow of flood waters into the system.
  • Be sure your system was designed and installed and is operated according to Minnesota Rules Chapter 7080.2270, which provides specifications for systems that are likely to withstand flooding during their lifespan. Install a backflow preventer (check valve) on the building sewer so sewage cannot back up into your home during a flooding event. Ensure your tanks have been installed in a manner that protects them against flotation from buoyant (upward) forces on the tank in saturated soil.

In preparation for imminent flooding
If your septic system requires electricity, turn off the pump and alarms at the circuit box before the area floods. Discontinue use of the system once the power supply has been shut off.
Waterproof all electrical connections to avoid electrical shock or damage to wiring, pumps, and the electrical system.

All system owners should make plans for severely limiting water use during and after the actual flooding event. Remember, well water may be contaminated and the soil treatment area may not accept water until the area dries. Normal water use should not continue until the area is unsaturated and a SSTS professional has visited the system to identify and repair any problems.

A tank can be pumped to reduce the amount of sewage that could back-up into the home. This is not necessary if a backflow preventer has been installed. Tanks in flood prone areas should be anchored to prevent buoyant forces from pushing the tank above the ground. This is a much larger concern if the tank has been recently pumped.

Additional Resources
Citizens can access the most up-to-date information on flood preparation by visiting Extension's website at www.extension.umn.edu/flood. Information about recovering from floods will be added as it becomes relevant.

Also available are Extension's toll free phone services, the Flood Information Line (1-800-232-9077) and the AnswerLine (1-800-854-1678). Extension's Flood Information Line is a resource for questions about water, crops, horticulture and climatology issues. Extension's AnswerLine provides answers to household and family-oriented questions, such as cleaning, mildew, and food safety issues.

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