REFERENCE: CHESTER COUNTY HEALTH DEPARTMENT PUBLICATION
Reason for Disinfecting a Water Supply
The reason for disinfecting a ware supply is to eliminate all harmful bacteria. Human beings and other warm blooded animals discharge such bacteria which may enter a water supply through the soil as a result of improper construction, leaks, repair work, flooding and seepage from sewage systems. An effort should be made to determine the cause of the problem. After the problem’s cause has been eliminated, the disinfection procedures can be used. If contamination problem persist, a permanent disinfection unit (chlorinator, Iodator or UV light) should be installed or a new well drilled.
Samples from new or repaired wells should not be submitted for bacteriological examination until the wells have been fully developed and disinfected with chlorine in an approved manner since the water is exposed to contamination during the construction or rehabilitation program. Likewise, when new pumping equipment is installed or the existing equipment is withdrawn from the well for repairs, a similar procedure should be followed.
Preparation of Disinfection
A. Sodium Hypochlorite
This chemical is in a liquid form and usually contains 5.5% of chlorine by weight. It is sold in stores as "Clorox", "Household Bleach", "White Sail" and by other trade name. It can be added to the well with little preparation.
Disinfection of Water Supplies
1. Pour the disinfecting agent into the well.
2. Pump the water through the water storage tank until the odor of chlorine comes out of all the water taps. If no odor should appear, add an additional quantity of disinfectant until a chlorine smell is noticed. Allow the disinfecting solution to remain in the well, storage tank and piping system for 12-24 hours by turning off the water pump and using no water. This could be done overnight or a day when no one is home.
3. After the disinfection time had elapsed, pump off a generous amount of water from the well each day until the odor of chlorine has disappeared. Care should be taken as to where this waste liquid is pumped as it might kill grass, flowers or life in streams, etc. Do not pump all this water into your septic system.
CAUTION: DO NOT DRINK THIS WATER UNTIL ALL CHLORINE IS PUMPED OUT OF THE LINES AND WELL. THIS MAY TAKE SEVERAL HOURS OF CONTINUOUS RUNNING OR SEVERAL DAYS OF RUNNING PART TIME.
4. Retest the water supply two-three days after the odor of chlorine has disappeared.