Necessary steps to take for private drinking water wells impacted by flooding

Floodwater and runoff from the recent heavy rains throughout some areas Nebraska may potentially carry multiple pollutants with it. During floods water comes in contact with many things it normally would not, including but not limited to untreated septic waste, animal waste, gasoline, chemical and fuel storage facilities, and more. If your private drinking water well has been impacted by floodwater, your water supply may have been contaminated with pollutants carried in the floodwater, thus making it unsafe for consumption.

Nebraska Extension’s Disaster Education team has put together water treatment options, including shock chlorination, for contaminated (or potentially-contaminated) water.

Wells at greatest risk of contamination from floodwater or surface water runoff include:

• Wells that were submerged with flood water or surface water runoff
• Wells located in a pit (where a wellhead, and possibly other well equipment, are located in a below-ground enclosure)
• Dug wells or any wells that do not have a watertight casing
• Wells that do not have watertight, secure cover or cap
• Wells constructed prior to 1986. (Prior to water well construction regulations in Nebraska, construction practices did not have a mandatory grout seal in the annular space around the well casing, making it less resistant to having surface runoff or floodwaters enter the well.)

Managing Wells after a Flooding Event

If you know or think your private drinking water well has been impacted by floodwater, follow the steps below. (Only follow steps 4-8 if you feel comfortable doing so.)

1. DO NOT USE well water for cooking, drinking or brushing teeth until laboratory analysis confirms it is safe
2. TURN OFF the power to all well equipment at the breaker panel
3. Wear waterproof, rubber-soled shoes or boots when inspecting around your wellhead and property — electricity and water can create a dangerous situation
4. Determine whether the wellhead was flooded 
   1. Inspect your wellhead for floodwater or signs of flooding disturbance. Debris and mud around the property, or water or mud stains on the wellhead, may indicate that the well was flooded.
5. Inspect the ground surface around the wellhead for erosion or instability
   1. Inspect the area around your wellhead for erosion or breaks in the ground that may lead to unsafe conditions, or a pathway for floodwater and contaminants to get in the well
6. Inspect the sanitary well cover/cap/seal and vent
   1. Note if the cover/cap and seal are securely fastened to the well casing. Look to see if the vent is still intact. Sediment and debris may enter the well through a loose well cap or vent and contaminate it if the wellhead was submerged.
7. Inspect the well casing
   1. Note if the exposed well casing appears to be bent, shifted, or cracked. Damages such as these may allow water, sediment, and debris to enter the well, thus increasing the risk of contamination.
8. Inspect electrical components, wiring, and conduit
   1. Make sure that power has been shut off to the well. Note if there are any exposed/damaged wiring or electrical components, or any signs the system has been submerged. Did water enter any of the electrical components?
9. If there are any signs of the above-mentioned conditions, no matter how slight, contact a Nebraska licensed water well contractor

Why it is important to contact a Nebraska licensed water well contractor for further inspection and repairs, and next steps to take:

1. Nebraska licensed water well contractors know Nebraska Regulations Governing Water Well Construction, Pump Installation, and Water Well Decommissioning Standards. They have gone through the examination process to become licensed to be a water well contractor in Nebraska. 
   1. An experienced Nebraska licensed contractor can identify problems that may not be apparent to the well owner
   2. Clean out any debris or sediment that entered the well
   3. Make repairs as necessary in accordance with state regulations
   4. Disinfect the well with shock chlorination. Allow the disinfectant to remain undisturbed in the well distribution system for at least 3 hours, preferably overnight. The system must be flushed after the disinfection process to remove any debris and flush contaminates from the water system before testing for drinkability.
   5. One to two weeks following shock chlorination, either the water well contractor or you must contact a certified testing laboratory and tell them you want to have your private water supply tested for bacteria due to flooding. They will provide a test kit with detailed instructions for collecting a sample and sample submission.
   6. Do not use the water from your well until the laboratory has informed you 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.

It is important to note that if floodwater came close to your well (100 feet or less) but did not reach the well, you should have your water tested as a precaution to protect the health of you, your family and your animals.

For more information on testing and treating water from a well that may have been contaminated by floodwater, see these UNL Extension NebGuides:

• Drinking Water Treatment
• Emergency Disinfection of Drinking Water
• Drinking Water: Testing for Quality
• Drinking Water: Bacteria
• Drinking Water Treatment: Shock Chlorination

More information can be found under Home, Health, and Safety — Water Well Safety of the Disaster Education website.