If your private drinking water well has been impacted by flood water, your water supply may have been contaminated with pollutants carried in the flood water. In addition, wells can be contaminated by surface water runoff even if the surrounding area is not flooded. Do not use the water for cooking, drinking, or brushing teeth until laboratory analysis confirms it is safe. (See water treatment options for household amounts and shock chlorination for well disinfection.)
Wells at greatest risk of contamination from flood water or surface water runoff include:
- Wells located in well pits.
- Dug wells or any wells that do not have a watertight casing.
- Wells that do not have watertight caps.
- Wells that lack a grout seal in the annular space.
- Wells that were submerged with flood water or surface water runoff.
Protect Wells from Flood Water
- Disconnect the power supply.
- If possible, have the well vent replaced with a water-tight plug, or have the casing permanently extended above flood level.
- Cover the top of the well with heavy-duty plastic and tightly secure it with waterproof tape (not duct tape) to keep debris and sediment out of the well, making post-flood clean-up easier.
- Prepare to have the well tested and disinfected (if needed) after flood waters recede.
- If cost-effective and feasible, consider disconnecting and moving expensive water system components such as the water heater and water treatment equipment.
- Sandbag for Flood Protection (eXtension resource)
- Water-Inflated Flood Barriers (eXtension resource)
Managing Wells After Flooding
If you think your private drinking water well was impacted by flood water:
- Do not use the water for cooking, drinking, or brushing teeth until laboratory analysis confirms it is safe.
- Contact a licensed well contractor. The contractor should:
- Inspect the well.
- Clean out any debris or sediment that entered the well.
- Disinfect the well with shock chlorination. The system must be flushed (three to four hours) after the disinfectant has been retained undisturbed in the system for six to eight hours to remove any debris and flush contaminates from the water system before testing for drinkability.
- Then, contact a certified testing laboratory and tell them you want to have your private water supply tested for bacteria. They will provide a test kit with detailed instructions. (See list of certified laboratories.)
- Don't use the water from your well until the laboratory has informed you that it is safe and free of bacterial contamination. It may be necessary to repeat the disinfection and testing process several times before the well is free of contamination.
If flood water came close to your well (100 feet or less) but did not reach the well, have your water tested as a precaution.
|Name of Lab||Certification #||Address||Certified for Analyses|
|American Agricultural Laboratory||NE-04-06||700 East D Street McCook, NE 69001||Total Coliform/E.coli by Colilert SM9223B Nitrate/Nitrite EPA 353.2|
|Central District Health Department||NE-04-01||1137 South Locust Grand Island, NE 68801||Total Coliform/E.coli by Colilert SM9223B|
|Enviro Services Inc.||NE-04-03||818 S. Beltline Hwy East Scottsbluff, NE 69361||Total Coliform/E.coli by Colilert SM9223B|
|Metropolitan Utilities Districts||NE-04-04||2710 Grebe Street Omaha, NE 68111||Total Coliform/E.coli by Colilert SM9223B|
|Midwest Laboratories, Inc.||NE-04-05||13611 B Street Omaha, NE 68144||Total Coliform/E.coli by Quanti-tray 2000 EPA SM92223B Nitrate as N by EPA 300.0 Rev 2.1|
Water Testing Kits
You can also order a water testing kit from the Nebraska Department of Health and Human Services.
Visit http://www.nebraska.gov/dhhs/water-test-kits/private.html to order a kit.
More Detailed Information
For more information on testing and treating water from a well that may have been contaminated by flood water, see these UNL Extension NebGuides:
- Water Treatment Options
- Drinking Water Treatment
- Emergency Disinfection of Drinking Water
- Drinking Water: Testing for Quality
- Drinking Water: Bacteria
- Drinking Water Treatment: Shock Chlorination
Information provided by: Bruce Dvorak, Environmental Infrastructure Engineer, University of Nebraska - Lincoln Extension