Wells usually need to be disinfected following initial installation or after some work is done on the system. Some wells may have a high sulfur or iron content which provides a source of bacteria, which may cause an unsatisfactory test result but may not cause disease. In such cases the problem may be cleared by heavy pumping for 12 - 24 hours or by disinfecting the well. The following procedure is designed for disinfecting a new well or one that has been contaminated during repair or some other problem.  It is not a solution to correct a contaminated water supply.

This procedure is designed for the typical 4-inch diameter well with a submersible pump. If you have an above ground jet pump with a closed system, you need to contact a well driller to disinfect the system.

1. Shut off power to pump and drain water from the pressure tank and all lines and tanks in the system.
2. Obtain one of the following:
   • One (1) pound of calcium hypochlorite. This may be purchased any place where pool chemicals are sold. This is the best type to use. You will need to mix the dry chlorine powder with approximately 5 gallons of water.
   • Two (2) gallons of liquid pool chlorine. (10 percent solution of sodium hypochlorite)
   • Four (4) gallons of plain household bleach (5 percent solution)
3. Remove one-half inch (1/2) plug from top of casing and pour chlorine solution into well through opening. Follow with 2 gallons of plain water. Allow solution to sit for approximately 1 hour.
4. Turn power on, start pump, and fill pressure tank. Open all faucets, one at a time, until bleach odor of chlorine is recognized, then close spigots.
5. Do not use any water from the system for 8 to 12 hours - water will have a high concentration of chlorine and may irritate sensitive tissue. Allow power to remain on to maintain pressure in tank.
6. After 8 - 12 hours, thoroughly drain and flush all lines and pressure tank, allowing water to run from spigots until no odor of chlorine bleach is present.
7. After another 8 hours, samples may be submitted to a laboratory for testing.

Should there be any questions regarding the above listed procedures, please call the Orange County Health Department, Division of Environmental Health at 407-521-2630.