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CORTLAND COUNTY HEALTH DEPARTMENT DIVISION OF ENVIRONMENTAL HEALTH 60 Central Avenue Cortland, New York 13045-2746 [PHONE REDACTED] Fax: [PHONE REDACTED] 1 Approved Labs in Cortland Area: Microbac, Cortland, [PHONE REDACTED]; Life Science Labs, East Syracuse & Binghamton [PHONE REDACTED]; Community Science Institute, Ithaca [PHONE REDACTED]; Yaws Environmental Lab, Ithaca [PHONE REDACTED] DISINFECTION OF WATER SUPPLY SYSTEMS Following the construction of a new well, spring, or other water supply, after repairs to an old supply, or after a supply has been temporarily contaminated with surface drainage, flood water, etc., it is advisable to disinfect the system by the use of a commercial chlorine compound such as chlorine bleach. The disinfection process outlined below will be successful in eliminating the effects of previous contamination, but will not continue to disinfect or render safe a water supply which is continuously or intermittently contaminated. Therefore, before disinfecting the water supply system, all sources of pollution should be eliminated. After proper repairs have been made, the supply should be flushed by opening all outlets one at a time . Allow the system to run freely to remove as much of the contaminating material as possible. The most convenient source of chlorine is ordinary unscented Clorox household bleach , but not splashless. Table 1. Bleach to be Mixed in 5 to 10 Gallons of Water Water Supply Type Water Depth or Volume Volume of Bleach (quarts) Drilled Well Less than 100 feet 1 Drilled Well 100 feet or more 2 Dug Well 3 feet or more 1 quart for every 3 feet Reservoir 150 gallons or more 1 quart for every 150 gallons Procedure for Disinfecting Well 1) Turn off electrical power to the well pump. Carefully remove well cap and seal if necessary. 2) Place a hose connected to an outside faucet inside the well casing , or water supply enclosure . Turn on electrical power to the well pump, and turn on hose faucet to run water back into the well. 3) Carefully pour the bleach mixture (See Table 1) into the well casing. Allow water from hose to continue to run into well. 4) At each outdoor and indoor faucet, run water until a chlorine odor is present, and then shut off each faucet. This will place chlorinated water into the pipes of the water system. If no chlorine odor is detected, repeat Step 3 above. 5) Return to well casing and rinse down inside of casing with water from the hose. Allow water to run into the well casing from the hose for one hour. 6) After one hour, turn off all faucets to stop the well pump. Turn off electrical power to the well pump. Remove the hose from the well casing. 7) Disinfect the well cap and seal by rinsing with a chlorine bleach and water mixture. Replace well cap and seal. Turn on electrical power to well pump. Allow the well to stand idle for at least 8 hours, and preferably 12 to 24 hours. Avoid using the water at that time. 8) After the well and the water in the pipes has idled for the recommended period of time, turn on an outside faucet connected to a hose and run water away from grass and shrubbery until the odor of chlorine disappears. Run all indoor and outdoor faucets until the odor and taste of chlorine disappears. If all the sources of contamination were eliminated before the disinfection, the water supply and system should now be safe for use. However, to be sure, a water sample should be taken to an approved lab 1 to check the bacteriological quality of water with a Total Coliform analysis . Call an approved lab or this department for instructions on taking water samples. Before sampling, be sure that all chlorine is out of the well. Chlorine content can be checked with a pool kit available where pool supplies are sold , or by waiting at least one week before sampling.