Is my well safe after a flood?

In some instances, the only place your groundwater is available is near a river or stream in a low-line area prone to flooding. Understanding your risks if your well is flooded is critical to protecting your family from contamination.

If floodwaters overtop your well, it's best to assume your well is contaminated. Once the water recedes, you should disinfect and sample your well for bacteria before using it again. You should also inspect your wellhead to be sure no debris gets into your well. This is a particular concern if your vent screen is missing. If you think there is debris, have a contractor clean and disinfect your well. If water reaches your well but doesn't overtop it, it's still safest to disinfect and sample prior to use. When inspecting your wellhead, be sure there is no evidence of water seeping into the ground along the well casing.

If your well is in a pit, well pits are a shock hazard, so be sure the entire pit is dry before entering after a flood. Your pit is a confined space, so have a qualified professional inspect and restart your system.

If there is any likelihood that floodwater could reach your well, you should plan in advance for that possibility and be prepared. Before floodwaters reach your well, disconnect the power supply to your well to prevent any electrical damage. If your pump is above ground — like in your basement or over the well — floodwaters could short circuit the system and even start the pump. You can also temporarily plug the vent to prevent any debris from getting into your well.

Septic systems can also be damaged or cause contamination during floods. Make sure the exit points are sealed. Your septic system should have a backflow preventer before the tank to keep sewage from backing up into your house during a flooding event. If your septic system has its own pump, be sure to shut off the power.

There are other, more permanent options that can help prevent flood contamination if you know your well is likely to be flooded. One is to have a contractor create an extension for your well to raise the pipe. We have seen wellheads in flood-prone areas that extend 10 feet or more above land surface. Water may still flood around your well but the integrity of the well cap and vent tube will not be an issue. Another option is to replace your vented cap with a waterproof one for just during the flood event. This may provide added protection, but it's still always best to test your water after the flood to be sure your well is not contaminated.

The Private Well Class is a collaboration between the Rural Community Assistance Partnership and the University of Illinois through the Illinois State Water Survey and is funded by the United States Environmental Protection Agency. The views expressed here are solely from the class authors and are not endorsed or reviewed by US EPA. For more information on private wells, sign up for our free 10-week email course at www.privatewellclass.org.