Properly Disinfecting Your Well
	Trumbull County Health Department Division of Environmental Health

During flooding events, water may enter well casings and get into the aquifer. This may cause the growth of microorganisms, thus contaminating the water supply. As a result, it is important for a homeowner to properly disinfect their well for coliform bacteria.

The following procedure should be followed for homeowners:

Step 1: Overpump

Turn on as many faucets in the home as possible, and run the water for several hours. The well should be heavily pumped to remove as much flood water as possible. When a well is flooded, the contaminated water enters the well and can move out into the geologic materials that supply water to the well. Overpumping will help remove flood water from the ground water supply.

Step 2: Mix Disinfecting Solution

Mix 2 gallons of fresh unscented laundry bleach (5.25% chlorine) with 5 gallons of fresh water.

Step 3: Pour Solution

Remove cap from well and pour solution directly into well.

Step 4: Add White Vinegar Solution

Mix 1 quart of white vinegar to another 5 gallon bucket of water. Add this solution to the well.

Step 5: Re-circulate

With a garden hose, re-circulate this solution back into the well, washing down the sides of the casing for about 10 minutes. Debris may begin to slough off the side of the casing and iron in the water may begin to turn solid as the chlorine reacts with it.

Step 6: Turn on All Faucets

Turn on all faucets connected from the well throughout the house and outside the house. Make sure to turn on both hot and cold faucets as well as faucets that rarely or never get used. Remember to run water into the washing machine and flush all toilets. Run the water until chlorine smell is detected. Do not by-pass the water softener or the water heater. Both must be disinfected as well. The resin bed of the water softener can provide a place for bacteria to grow. Remove and discard any carbon filters or cartridge filter elements and thoroughly clean the inside of the filter housing.

Step 7: Disinfection

Once the odor of chlorine is detected, shut off the faucets and let the water sit in the plumbing for at least 24 hours to allow disinfection to occur.

Step 8: Flush

After 24 hours, of sitting in the lines, flush the well out as follows:

Run an outside spigot for several hours until chlorine odor is gone. Do not flush water down the septic tank to prevent high levels of chlorine from damaging septic tank. Turn on each faucet and run until chlorine is gone in each faucet (should only take a few minutes on each faucet).

Step 9: Wait 48 hours, then sample

Wait 48 hours and sample for coliform bacteria. Make sure that the water is checked for chlorine before requesting the water sample. If there is any indication of chlorine in the water, the Health Department will not test at that time. (Health Dept. will pretest for chlorine residuals). Do not replace carbon filters or filter elements until the coliform sample is negative

Note: There are many instances where the previously described disinfection procedures may not work in making a well bacteria-free. If a positive result occurs you may need to repeat the process. If coliform persists in water samples after two chlorinations, contact an experienced private water systems contractor to professionally pressure chlorinate your well.

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