How to Treat Wells With Coliform

If your home uses a private well water system, it is essential that you test it annually to ensure sanitary, safe water. The total coliform test is among the most important water quality measurements. While coliform bacteria are not necessarily harmful, they are an indicator species that suggests the presence of pathogenic organisms found in human or animal waste. Anytime your well water tests positive for coliform, you should discontinue water use in your home until you can disinfect your well using shock chlorination.

Things You'll Need

• 5 percent sodium hypochlorite (household bleach)
• Wrench
• Rubber hammer
• Funnel

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Instructions

• 1

  Refer to the measurements recorded on the well tag to determine the height of the water column. Subtract the depth of the water level from the well's total depth. For example, a 100-foot well with a water level 20 feet below ground level has an 80-foot water column.

• 2

  Determine the volume of your well's water column. Multiply the height of the water column by the gallons of water per foot of casing, which is dictated by the casing's diameter. For example, a 6-inch diameter casing contains 1.5 gallons of water per foot of length, so a 70-foot water column would contain 105 gallons. (Refer to the References section for a document with a helpful table.)

• 3

  Add 100 gallons of water to the aforementioned figure, assuming that is the effective volume of your household plumbing system. Finally, divide this total by 100 gallons, and then multiply by 6 ounces to determine the amount of household chlorine bleach that is appropriate for your well. Pour the bleach into 4 to 5 gallons of water in a bucket and mix to prepare your final solution.

• 4

  Loosen and remove the well seal to give you access to the casing beneath. Use a wrench (and a rubber mallet, if necessary) to unseat the seal. If this proves too difficult, simply uncover a plughole or unscrew the vent pipe to expose the vent hole.

• 5

  Pour your chlorine solution into the well, either directly into the casing or into the vent hole using a funnel. Let the solution sit for 15 minutes.

• 6

  Run a garden hose from the well output back into the chlorine entry point, and circulate water through the well until you detect a strong chlorine odor from the hose water. Likewise, run every faucet in your plumbing system connected to the well until it smells noticeably of chlorine.

• 7

  Turn off each discharge point and let the chlorine solution sit in your pipes for at least eight hours. Do not use your plumbing during this period, to avoid flushing chlorine into your septic tank.

• 8

  Flush the chlorine from your plumbing system by running an outdoor faucet continuously until the smell of chlorine is no longer detectable. Drain the bleach solution at a safe distance from plants, storm drains and bodies of water. Then open the faucets in your house until they smell neutral again.

• 9

  Test your well water again in a week. If it tests positive for total coliform, repeat the chlorination process and inspect the well for possible bacterial entry points. Inspect the integrity of the well seal and the casing, as well as the environment around the well. Look for a concentration of animal feces or changes in hydrological patterns.