Flooding is the most common natural occurrence that can impact the function and safety of a well. In the wake of Hurricane Matthew, the National Ground Water Association issued an important reminder that one must assume that a flooded well has been contaminated by bacteria. Cliff Treyens, NGWA's director of general public outreach, offers these tips to homeowners with flooded wells: Do not drink the water or wash with it. Use an alternative supply. such as bottled water. Stay away from the well pump while it’s flooded to avoid electrical shock. Get a qualified water well contractor or pump installer to clean and turn on the pump, flush the well, disinfect the well, and perform any other necessary maintenance. Check with the local emergency management agency about any guidance relating to local conditions or specific contamination threats due to area flooding. This video, also from NGWA, explores the topic further: You can also refer to Chapter 6 of The Private Well Class . Here's the excerpt on flooding: "If flood waters overtop your well, assume your well is contaminated. Once the water recedes, you should have your well disinfected and sampled for bacteria before using it again. Remember to disconnect any inline treatment prior to disinfection. You should also inspect your wellhead to be sure no debris got 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. If you have the luxury of knowing a flood could happen, be prepared. Store a supply of clean water that you can use during and after the flood. Disconnect the power supply to your well to prevent any electrical damage from short circuits. Temporarily plug the vent holes to prevent debris from getting into your well. There are other options that can help prevent flood contamination, but they are more costly. 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. 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 have a sample analyzed after the flood to be sure there were no leaks or other avenues into the well that flood waters may have found. Well pits are a shock hazard, so be sure the entire pit is dry before entering. If your pit is a confined space, then do not go into it because of the risk of dangerous gases. Have a qualified professional inspect and restart your system. If your pump is above ground, like in your basement or over the well, flood waters could short circuit the system and even start the pump. Be sure the power is off in advance of the flood, and have your pump checked and tested by a professional before using it again. Septic systems can also be damaged or cause contamination issues during floods. Make sure the access points are sealed. Your septic system should have a backflow preventer before the tank to keep sewage from backing up into your home during a flooding event. If your septic has its own pump, be sure to shut off the power."