Please read the following instructions before beginning disinfection of the water supply: 

Purchase 12 to 24 ounces of HTH, Lo-Bax, BK powder, or other sanitizing agent containing calcium hypochlorite. If you know the depth and diameter of the well, you may contact our Department for a more exact quantity of calcium hypochlorite to add.  Hardware stores, farm supply stores, home improvement stores, swimming pool product suppliers and drill shops usually carry this type of concentrated chlorine disinfectant. Achieving a chlorine concentration of 100 parts per million in your water is the standard method of disinfection. The Division of Water Quality, Aquifer Protection Section recommends that household bleach, stabilized chlorine tablets, or hypochlorite products containing fungicides, algaecides, or other disinfectants should NOT be used. 

CHLORINE IN HIGH CONCENTRATIONS CAN BE HAZARDOUS TO HUMANS AND TO THE ENVIRONMENT.  Please follow the manufactures recommendations for use, storage and disposal. 

The following steps should be taken to ensure that the well and water supply is thoroughly disinfected: 

1. Mix calcium hypochlorite in a five (5) gallon container of water. Mix thoroughly in a well-ventilated area or outdoors. 
2. Pour this mixture into the well and try to let the mixture hit the inside of the well casing and lid as much as possible.  The well should have an air vent that can be easily removed.  Place a funnel or similar device in the air vent slot and pour this mixture down into the well.  
3. If you plan on removing the well head seal (our Department strongly recommends only a N.C. certified well contractor remove a well head seal), you may use a garden hose to help disinfect the walls of the well casing. After adding the calcium hypochlorite solution to the well, cut on the water hose. Once chlorine is smelled coming out of the hose, rinse the inside of the casing and well lid. 
4. If possible, circulate the disinfectant throughout the well by placing the hose inside the well (or attach the hose to the funnel) and turning the water supply on. Circulate the disinfectant for 2-3 hours if possible.
5. Place the air vent/well head seal back on the well.  Be sure that the well is properly sealed. 
6. Cut on all the faucets in the house one at a time until a chlorine odor is detected.  As soon as you can smell chlorine, cut the tap off.  Do not use any water for at least 24 hours.  This allows contact time for the chlorine to kill bacteria in the well and water lines. 
7. After at least 24 hours, hook a garden hose up to an outside faucet and pump the chlorine out of the well. It is best to run the mixture either into a road ditch or the woods. Don’t run it into the septic tank or spray it on your lawn since it will upset the bacteriological balance in the septic tank or kill your grass. Run the water until there is no chlorine odor detected.  Someone should be present during this process to avoid pumping the well dry and damaging the pump. 

At least seven days after the chlorine has been removed from the water supply, notify the Environmental Health Section and we will resample your water supply as soon as possible. You may contact an Environmental Health Specialist Monday through Friday at 570-6367 between 7 and 9 am, if you have any questions.