Flood Recovery for Rural Areas - part 5

Water Contamination in Private Wells

Repair, Clean-Up and Disinfection

Wells that have been overtopped by floodwater pose a number of immediate dangers, from electrical shock to serious water-borne illnesses. Therefore, do not turn on your pump after flooding has occurred and do not drink or wash with well water. Your well and pump need to be inspected after a flood. Your well also needs to be properly disinfected and its water tested for safety.

Well and Pump Inspection

Swiftly moving floodwater can carry large debris that could loosen well hardware, dislodge well construction materials or distort casing. Coarse sediment in the flood waters could erode pump components. In some cases, floods may cause some wells to collapse. For all these reasons, you should have professionals inspect your system.

Electrical system. 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 cleaned and dry before electrical service can be restored. Get assistance in turning the pump on from the well or pump contractor.
Pump operation. All pumps and their electrical components may be damaged by sediment and floodwater. The pump, including the valves and gears, needs to be cleaned of silt and sand. If pumps are not properly cleaned and lubricated they can burn out. Get assistance from a well or pump contractor who can clean, repair and maintain different types of pumps.
Submersible pumps. The bearing on water-lubricated pumps will not be damaged by flood waters, since these bearings are constantly submerged in water. As soon as possible, flush clean water down the casing to remove sediment and silt. The disinfect the well.
Centrifugal pumps. Many centrifugal pumps contain two sets of oil-lubricated bearings along the drive shaft between the motor and the pumps. If the pump has been flooded, dismantle the container bracket and remover the bearings.
Clean the bearing or install new bearings if the old ones are worn out.
Close-coupled centrifugal pumps contain no bearings, so there is little chance of flood damage except to the electric motor.
Injector-type pumps. These pumps usually contain watertight packing at the ground surface, with sealed impellers. Flood waters probably will not damage this type of pump.
General cleaning of drilled, driven or bored wells. To avoid damage to the well, have the contractor remove mud, silt and other debris from around the well top. If excessive mud, silt or sediment has entered the well, the pump may need to be removed before cleaning can take place.
The storage tank and piping should be all right unless muddy water was pumped through it. If tank is contaminated, disinfect the entire system with a strong chlorine solution. Use one quart household laundry bleach or check with local health department for recommended solution strength. Open all faucets while the system is being filled. Do not close the spigot until a definite smell of chlorine is evident. Don not use the system for 24 hours. Then start the pump and run water from all faucets until the chlorine odor is gone.
Dug wells. Do not attempt to disinfect or use a dug well that has been flooded.

Pumping the Well

After the contractor services and cleans the well, pump it until the water runs clear to rid the well of floodwater. Depending on the size and depth of the well and extent of contamination, pumping times will vary. If the water does not run clear, get advice from the county or state health department or Extension service.

Emergency Disinfection

After flooding, a well must be disinfected to kill bacteria and other potential disease-causing organisms. Wells that are less than 50 feet deep may be contaminated even if there is no apparent flood damage. The following steps apply to drilled, driven or bored wells only. Disinfection should not be attempted for dug wells.
Follow the instructions above for pumping the well.
Prepare a chlorine solution. Approximately 8 quarts of 5.25-percent (or 5 quarts of 10 percent) chlorine bleach such as Hilex, Clorox, etc., should be mixed with 100 gallons of water. It is best to prepare more solution than the amount of water standing in the well; if this amount is unknown, the 100-gallon measure is a safe estimate. Most garbage cans hold 30 gallons or more; therefore, filling three (clean) cans with the solution is sufficient.
Pour or pump the solution in the well in one continuous flow. Attach a hose to a faucet and, making certain the hose itself is clean, place the other end of the hose into the well. Open the faucet and recirculate the chlorinated water for one hour, washing down the inside of the casing and pump piping. Faucets in your house should be opened until you detect a chlorine smell, then close them.
Allow the chlorine solution to remain in the well and piping for at least 24 hours, preferably longer. The system should then be purged free of chlorine. Since it can disrupt a septic system, the chlorinated water should be run outdoors, perhaps into a ditch. It may kill grass and shrubs, and should not be run into a lake or stream.

Sampling and Testing

Once all flooded wells have been disinfected, wait one week to have the water sampled and tested by a state-certified laboratory or health department. Do not drink the water until two consecutive tests come back safe.
If the laboratory issues sterile bottles for sampling, carefully follow all instructions for their use.
If the test comes back unsafe, disinfect again.
If the test comes back safe, retest in two weeks. Unfortunately, your well may not be a safe source of water for months after extensive flooding or high groundwater. Wastewater from malfunctioning septic tanks or chemical seepage can contaminate the groundwater even after water was tested and found to be safe. You need to take long-range precautions, including repeated testing, to protect the safety of drinking water. Keep in mind that even under normal conditions, all private wells should be tested annually.

Flooded Private Sewage Systems

Safety, Sanitation and Clean-Up Concerns

Flooding of a private sewage system can be a hazardous situation for homeowners. It may lead to a back-up of sewage in the home, contaminated drinking water and lack of sanitation until the system is fixed. While you don't have control over rainfall or flooding in your area, you can prepare for high water problems and respond appropriately to emergency flooding.

How Problems Occur

When flooding or saturated soil conditions persist, a private sewage system cannot function properly. Soil treatment systems for wastewater rely on aerobic (with oxygen) regions to reduce the amounts of chemicals and living organisms (viruses, bacteria and protozoa). When the soil is saturated or flooded, those hazardous materials can enter the groundwater and your drinking water supply.

After the Flood

Do not use the sewage system until water in the disposal field is lower than the water level around the house.
If you suspect damage to your septic tank, have it professionally inspected and serviced. Signs of damage include settling or inability to accept water. Most septic tanks are not damaged by a flood since they are below ground and completely covered. However, sometimes septic tanks or pump chambers become filled with silt and debris, and must be professionally cleaned. If tile lines in the disposal field are filled with silt, a new system may have to be installed in new trenches. Because septic tanks may contain dangerous gases, only trained specialists should clean or repair them.
Discard any items that are damaged by contaminated water and cannot be steam cleaned or adequately cleaned and disinfected.
Do not pump water out of basements too quickly. Exterior water pressure could collapse the walls.
If sewage has backed up into the basement, clean the area and disinfect the floor with a chlorine solution of one cup of chlorine bleach to 1 gallon of water.
Contact the county health department for information on well testing. Do not drink the water until it has been tested and is safe.