Flood Protection for Well Owners: Before, During and After a Flood
A flood can push bacteria, fuel, fertilizer and septic waste straight down a well casing. Most of the damage is preventable — and what you do in the first days afterward decides whether your family drinks safe water. This guide pulls together official advice from the EPA, CDC, Ready.gov/FEMA and state health departments.
Flood checklist for well owners
- ☐ Wellhead above flood level, casing 12+ inches above ground, soil sloping away
- ☐ Sealed, vented, screened sanitary well cap
- ☐ Fuel, fertilizer and pesticides stored away from the well
- ☐ You know where the well pump breaker is
- ☐ Stored drinking water (1 gallon per person per day, several days)
- ☐ Flood threatening? Shut off pump power. Don't drink the well water.
- ☐ After: electrician/well contractor checks pump before power-on
- ☐ Shock-chlorinate, flush, then test for total coliform / E. coli (and nitrate) at a certified lab
- ☐ Retest 1–2 weeks later; check your septic system
Before a flood: protect the well
- Raise and inspect the wellhead. The casing should extend at least 12 inches above the ground (higher if your area floods), with soil mounded so water drains away from it rather than pooling around it.
- Use a sanitary well cap. A sealed, vented and screened cap keeps out floodwater, insects and small animals. Replace cracked or loose caps.
- Seal around the casing. Gaps between the casing and the ground let surface water run straight down to the water table.
- Move contaminants away. Store fuel, fertilizer, pesticides and chemicals far from the wellhead and above flood level. Know where your septic tank and drain field are relative to the well.
- Know your shutoff. Label the breaker for the well pump so anyone in the house can turn it off.
- Store drinking water. Ready.gov recommends at least one gallon per person per day for several days.
During a flood
- Shut off power to the well pump if floodwater threatens the well or the electrical system.
- Don't drink or cook with well water. Use stored or bottled water.
- Avoid contact with floodwater — it can carry sewage, chemicals and live electrical current.
After a flood
- Don't switch the pump back on until it's dry and checked. Submerged pumps and wiring are a shock hazard; have an electrician, well or pump contractor inspect them.
- Assume the water is contaminated if floodwater covered the wellhead or reached the well. Until tested, use bottled water or boil water at a rolling boil for 1 minute.
- Have the well inspected for damage to the cap, casing and seals.
- Shock-chlorinate (disinfect) the well following CDC's well disinfection steps or your state's instructions, using unscented household bleach.
- Flush until the chlorine odor is gone (drain away from plants and streams).
- Test with a certified lab for total coliform and E. coli — and nitrate if farm fields or septic systems are nearby. CDC advises waiting 7–10 days after disinfection so chlorine doesn't skew results. Find a lab in your state.
- Retest 1–2 weeks later to confirm the water stays clean.
- Check your septic system. Don't use it while the drain field is saturated; see EPA's septic guidance after a flood.
More detail on bacteria testing: Coliform bacteria in well water after a flood.
Protecting the rest of your property
- Grading and drainage: slope soil away from the house and well; keep ditches and culverts clear.
- Gutters and downspouts: clean them and extend downspouts several feet away from the foundation and wellhead.
- Sump pump: test it, add a battery backup, and install a backflow (check) valve so sewage can't back up into the house.
- Flood barriers: keep sandbags or removable barriers on hand if you're in a flood-prone area.
- Elevate utilities: raise the furnace, water heater, electrical panel and well pressure tank above expected flood levels where possible.
- Anchor fuel tanks so they can't float, tip or leak.
- Flood insurance: standard homeowners policies usually don't cover flooding. NFIP policies are available through FloodSmart.gov and typically take 30 days to take effect — buy before the season, not before the storm.
- Emergency kit: water, food, medicine, flashlight, radio and documents — see Ready.gov's kit list.
- Document your belongings with photos or video before a flood to speed up insurance claims.
Official sources
- U.S. EPA — What to Do With Your Private Well After a Flood
- U.S. EPA — Protect Your Home's Water
- CDC — How to Disinfect Wells After an Emergency
- Ready.gov (FEMA) — Floods
- FloodSmart.gov — National Flood Insurance Program
- Minnesota Department of Health — Disinfecting Flooded Private Water Wells (PDF)
- New York State Department of Health — Restoring and Testing Your Private Well After a Flood
Free well water safety checklist
15 family-friendly steps based on CDC and EPA guidance. Print it, keep it on the fridge, and know when to call a certified lab.
More guides
- PFAS “Forever Chemicals” in Private Wells: Why You Should TestFederal PFAS rules protect public water systems — not private wells. Here’s what “forever chemicals” mean for well owners and how to get tested.
- Nitrates in Well Water and Blue Baby Syndrome: Who Must TestNitrate in well water can cause blue baby syndrome in infants. Learn who is at risk, when to test, and how to find a certified lab.
- Arsenic in Private Well Water: The Invisible Risk UndergroundArsenic in groundwater is often naturally occurring and invisible. USGS research shows millions of private-well users may be above the EPA drinking-water standard.
- Lead in Well Water: Old Pumps, Plumbing, and Why Taste Won’t Warn YouLead doesn’t change how water looks or tastes. If your home has older plumbing or well equipment, testing is the only way to know your exposure.