Flood season testing for private wells
Most US flooding happens from spring snowmelt through summer storms and the fall hurricane season. Every flood that reaches a wellhead can carry bacteria into your drinking water — and you can't see, smell or taste it.
When to test
- Right after the water recedes — don't drink the well water until it's disinfected and tested.
- 7–10 days after disinfecting (shock chlorination), once the chlorine is flushed out: test for total coliform and E. coli, plus nitrate near farms or septic systems.
- Again 1–2 weeks later to make sure the water stays clean.
- Once a year anyway — the EPA recommends annual testing for bacteria and nitrate.
Get your well tested
Use a state-certified drinking water lab. Many county health departments offer low-cost bacteria tests after floods — your state page lists certified labs and official programs.
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Read more: Flood protection for well owners · Coliform bacteria after a flood
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