Homeowners with water wells need to take special precautions and actions in the aftermath of hurricanes. Because of the extensive flood area and the speed and direction of ground water flow, your well may not be a safe source of water for many months after a flood. The well can become contaminated with bacteria or other contaminants.
Waste water from malfunctioning septic tanks or chemicals seeping into the ground can contaminate the ground water even after the water was tested and found to be safe. It will be necessary to take long-range precautions, including repeated testing, to protect the safety of drinking water.
Swiftly moving flood water can carry large debris that could loosen well hardware, dislodge well construction materials or distort casing. Coarse sediment in the floodwaters could erode pump components. If the well is not tightly capped, sediment and floodwater could enter the well and contaminate it. Wells that are more than 10 years old or less than 50 feet deep are likely to be contaminated, even if there is no apparent damage. Floods may cause some wells to collapse.
Also, after floodwaters have receded and the pump and electrical system have dried, do not turn on the equipment until the wiring system has been checked by a qualified electrician, well contractor, or pump contractor. If the pump's control box was submerged during the flood all electrical components must be dry before electrical service can be restored. Get assistance in turning the pump on from a well or pump contractor.
All pumps and their electrical components can be damaged by sediment and flood water. The pump including the valves and gears will need to be cleaned of silt and sand. If pumps are not cleaned and properly lubricated they can burn out. Get assistance from a well or pump contractor who will be able to clean, repair or maintain different types of pumps.
Turning on the pump poses danger of electrical shock and damage to your well or pump if they have been flooded. Also, do not wash with well water. People drinking or washing with water from a private well that has been flooded will risk getting sick.
Drilled, driven or bored wells are best disinfected by a well or pump contractor, because it is difficult for the private owner to thoroughly disinfect these wells.
If you suspect that your well may be contaminated, contact your local or state health department or agriculture extension agent for specific advice on disinfecting your well. The suggestions below are intended to supplement food precautions issued by state and local health authorities.
The EPA offers the following instructions for the emergency disinfection of wells that have been flooded:
First, before disinfecting the well: Check the condition of your well. Make sure there is no exposed or damaged wiring. If you notice any damage, call a professional before the disinfection process.
- Step 1: If your water is muddy or cloudy, run the water from an
outside spigot with a hose attached until the water becomes clear and free of
Step 2: Determine what type of well you have and how to pour the bleach into the well. Some wells have a sanitary seal with either an air vent or a plug that can be removed. If it is a bored or dug well, the entire cover can be lifted off to provide a space for pouring the bleach into the well.
Step 3: Take the gallon of bleach and funnel (if needed) and carefully pour the bleach down into the well casing.
Step 4: After the bleach has been added, run water from an outside hose into the well casing until you smell chlorine coming from the hose. Then turn off the outside hose.
Step 5: Turn on all cold water faucets, inside and outside of house, until the chlorine odor is detected in each faucet, then shut them all off. If you have a water treatment system, switch it to bypass before turning on the indoor faucets.
Step 6: Wait six to 24 hours before turning the faucets back on. It is important not to drink, cook, bathe or wash with this water during the time period -- it contains high amounts of chlorine.
Step 7: Once the waiting period is up, turn on an outside spigot with hose attached and run the water into a safe area where it will not disturb plants, lakes, streams or septic tanks. Run the water until there is no longer a chlorine odor. Turn the water off.
Step 8: The system should now be disinfected, and you can now use the water.
Step 9: Have your water tested for bacteria seven to 10 days after disinfection.
Materials needed are one gallon of non-scented household liquid bleach, rubber gloves, eye protection, old clothes and a funnel.
If in doubt about the well water supply, follow health department drinking and bathing advisories. Remember that there is a danger of electrical shock from any electrical device that has been flooded; consult a certified electrician. Rubber boots and gloves are not adequate protection from electric shock.
Well disinfection will not provide protection from pesticides, heavy metals and other types of non-biological contamination. If such contamination is suspected, due to the nearness of these contaminant sources, special treatment is required.
Information on home water treatment units is available from EPA by phone (800-426-4791) or the U.S. EPA's hurricane website: http://www.epa.gov/region6/disaster/pdf/private_wells.pdf.