HomeMy WebLinkAboutDisinfection InstructionsCONTAMINATED DRINKING WATER
Laboratory testing of your water sample shows the presence of coliform bacteria. Coliform bacteria consist of
two groups: Total and Fecal.
The Total Coliform groups are those coliform bacteria that do not live readily in the intestinal tract of animals.
When present they typically indicate surface water or seepage water contamination of your well since they are
found in soils and on vegetation.
The Fecal Coliform groups are those coliform bacteria that live only in the intestinal tract of animals. When
these are present, they likely indicate that sewage contamination is entering your water supply.
The presence of either or both coliform groups indicates that a pathway into your water supply exists through
which disease-causing bacteria can enter. Therefore, it is important that all water used for consumption
(including that used for making ice) be boiled for one (1) to two (2) minutes. The source of contamination
should be identified. Untreated water can be used again when the water shows no contamination of coliform
bacteria by laboratory testing.
COMMON CAUSES OF WATER SUPPLY CONTAMINATION
Poor Well Construction – Bad sanitary seal (well cover); open holes in the well cover where wires enter; cracks
in the casing or casing welds; poor grouting around your well.
Poor Well Location – Is your well within 100 feet of a sewage disposal system? Is your well located in a
depression or a pit with no way to evacuate floodwater? Do you flood irrigate around your well or pump house?
Is your well located within 100 feet or an animal confinement area?
Well Depth – Shallow wells typically do not produce good quality water as they are often subjected to surface
contamination. If this is causing your problem the well can be deepened or a new one should be drilled. Is your
well located in heavily fractured rock-like lava or limestone? Fractures provide easy pathways for
contamination to travel long distances.
DISINFECTION OF WELLS
1. Mix one (1) gallon of household bleach with four (4) gallons of water in a large bucket. This dilution
is recommended because bleach by itself is extremely corrosive and can potentially be damaging to
any materials in which it is directly exposed.
2. TURN OFF THE POWER TO THE WELL and pour the mixture directly into the well casing.
3. Open all taps (hot and cold) inside and outside of your home, one at a time, until you smell the
bleach. Once the bleach odor is detected, shut off that tap and move on to the next one.
4. Flush each toilet until a bleach odor is detected in the toilet’s water tank.
5. Once all taps have detectable bleach odors in them, let the entire system sit unused for at least
twenty four (24) hours.
6. Flushing out the bleach solution:
a. Open outside taps first and let water run until the smell of chlorine is no longer detected. This
is necessary as it is undesirable to flood your sewage system with chlorine.
b. Flush all other taps next - hot and cold - until the smell of chlorine is no longer detected.
7. Allow three (3) days of normal water use prior to collecting another sample for bacterial testing.
If you are still in doubt about the safety of your water system, please call Andrew Well Drilling (208–522-2794)
or Denning Well Drilling (208-523-4600) for further assistance.