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 Likewise, when new pumping equipment is installed or the existing equipment is withdrawn from the well for repairs, a similar procedure should be followed.

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.

Method:

1. Add about ½ pint to a bucket of cold water and stir well. Note: A minimum of four buckets of disinfecting solution is added to a water supply for disinfection.
2. Do not permit the solution to be exposed to light for a long period of time. B. Chloride of "Lime This" substance is a white powder containing about 30-33% chlorine by weight. It absorbs moisture readily and therefore must be kept tightly sealed container.
3. Method:

   1. Take a 10 ounce can of Chloride of Lime and dump the contents into a clean bucket.

   2. Add about one quart of water and stir thoroughly with a wooden stick to form a uniform past which should be free of lumps.

4. Add about two gallons of water and mix thoroughly.
5. Let mixture stand until the insoluble material settles to the bottom.
6. Pour off the clear solution into another bucket. This is to be added to the water supply for disinfection.

Disinfection of Water Supplies

Procedure:

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.

4. Retest the water supply two-three days after the odor of chlorine has disappeared.

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