How to properly shock a well for coliform or e.coli bacteria is a question that comes up on a daily basis. So I’ll go through a few steps on how to do it correctly.

Step #1
Flush well for 10 minutes, longer if well is over 150ft deep.

Step #2
Size your well. Your well depth will determine how much chlorine (bleach) to use to shock it. As a general rule use the following amount of chlorine; amount may vary if shocking for coliform and/or e.coli or if shocking for iron bacteria:

  • 30ft = 1.5 cups
  • 60ft = 2 cups
  • 100ft = 2.5 cups
  • 130ft = 3.5 cups

If you don’t know your well depth use 2 cups.

Step #3
Mix chlorine (or unscented bleach) in a 5 gallon bucket.

Step #4
Remove well cap or vent; using a funnel if needed pour chlorine mixture into well.

Step #5
Run outside hose for 1-2 minutes until you smell chlorine.

Place hose into well opening and run for 10 minutes, (longer with deeper wells).

Step #7
Let chlorine sit for 2 hours. (5 hours when dealing with iron bacteria)

Step #8
Using the same hose, flush well OUTSIDE the house for 20-30 minutes or until smell dissipates.

IMPORTANT: Well must be flushed (purged) outside the house, do not let this water into the house. (See How to Disinfect Household Plumbing)