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.
Flush well for 10 minutes, longer if well is over 150ft deep.
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.
Mix chlorine (or unscented bleach) in a 5 gallon bucket.
Remove well cap or vent; using a funnel if needed pour chlorine mixture into well.
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).
Let chlorine sit for 2 hours. (5 hours when dealing with iron bacteria)
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)