Well Water After a Flood: A Step-by-Step Safety Guide

If floodwater reached your well, treat the water as unsafe. Here's the order health departments recommend: stay safe, clear the water, disinfect, test, and test again.

Step-by-step

1. Wait for the water to go down. Connecticut's guidance says not to disinfect until floodwaters recede.
2. Check the electrics. If the pump, wiring or control box was underwater, have an electrician or pump contractor inspect it before switching it on.
3. Inspect the wellhead. Look for a missing or damaged cap, debris, or a damaged casing. Dug and bored wells are most at risk.
4. Run the water until it's clear. Use an outside spigot with a hose, not indoor drains, especially if you have a septic system.
5. Shock chlorinate the well with unscented bleach, following Penn State's procedure, or hire a licensed well contractor, which is often best for drilled wells.
6. Let it sit, then flush. South Carolina's guidance says to run taps until you smell chlorine, wait 6–24 hours, then flush until the chlorine smell is gone.
7. Test for bacteria 7–10 days later (total coliform and E. coli) at a certified lab. Ask your health department, since many offer free flood testing.
8. Keep testing. Georgia's guidance warns a flooded well may not be safe for many months, so retest even after a clean result.

What else floodwater can bring

• Sediment and cloudiness: see cloudy water and sand and sediment.
• Nitrate from fields and septic systems: test it if you're in a farming area or have an infant.
• Fuel or chemicals: if you smell fuel or solvents, tell your health department and don't use the water.

Protect the well for next time

• Make sure the casing extends above the ground and the expected flood level, with a sealed, vermin-proof cap.
• Grade the ground so water drains away from the wellhead.
• Keep a record of your well's location, depth and last test results.

Related problems

• Sewage smell
• Cloudy water
• Sand and sediment