Fact Sheet: Well Disinfection
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KNOW THE FACTS!
When to Disinfect
All newly constructed and existing water supplies which have been replaced, reconstructed, flooded, or reactivated after a period of shutdown must be disinfected to guarantee a safe drinking water supply.
What to Use
Sodium hypochlorite or liquid laundry bleach (3 percent or 5.25 percent chlorine); unscented.
The solution – Make a five gallon batch:
- two gallons 3 percent laundry bleach in three gallons water
- one gallon 5.25 percent laundry bleach in four gallons water
- Stop pump. Remove well cap, vent pipe, or plug if well is equipped with a sanitary well seal.
- Small wells (12″ or smaller diameter): use half of prepared solution. Large wells: use entire five gallon batch.
- Start pump. Connect a hose to a house spigot and run water directly into the well. Continue until chlorine odor is present in the water running from the hose. Run water for 15 minutes.
- Shut off water supply to hose. Open all taps (include all cold and hot water valves, remember basement fixtures). Allow water to run until each tap has a distinct chlorine odor. Close taps. Stop pump. Add remainder of solution to well or a second batch if large well.
- Allow to stand for 12 to 24 hours. The retention time of the solution is crucial for the disinfection process.
- Start pump. Open all taps. Allow water to run until chlorine odor disappears.
- Request your local health department to collect samples and approve your water before using.
For more information, call the Water Quality Division at 513.946.7966 or visit www.hamiltoncountyhealth.org.
Download a printable version of this fact sheet here.
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