Water well owners need to take special precautions and actions in the aftermath of hurricanes. The U.S. Environmental Protection Agency (EPA) has issued a statement concerning the steps that should be taken to ensure a safe return to water well operation. Because of the extensive flood area, and the speed and direction of ground water flow, water wells may not be a safe source of water for many months after the flood. The well can become contaminated with bacteria or other contaminants.
Wastewater 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 floodwater 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. If the pump’s control box was submerged during the flood, all electrical components must be dry before electrical service can be restored.
All pumps and their electrical components can be damaged by sediment and floodwater. 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.
Turning on the pump poses danger of electrical shock and damage to the 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.
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 the water is muddy or cloudy, run the water from an outside spigot with a hose attached until the water becomes clear and free of sediments.
Step 2: Determine 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 there is a water treatment system present, switch it to bypass before turning on the indoor faucets.
Step 6: Wait 6 hours 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 off the water. The system now should be disinfected, and you now can use the water.
Step 8: Have the water tested for bacteria 7 days to 10 days after disinfection.
Remember that there is a danger of electrical shock from any electrical device that has been flooded; 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.