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When Floodwater Reaches the Well or the Septic Tank
After a flood, don't drink well water until the well has been disinfected and tested, and don't pump a septic tank while the ground is saturated. Cut water use and call the county health department.
East of Lake Jesup, in Geneva, Chuluota and the Black Hammock area, a lot of homes depend on two systems that sit in the same yard: a private well and a septic tank. One flood can reach both. Statewide, the Florida Department of Environmental Protection counts about 2.6 million septic systems serving roughly 30% of Floridians, so this isn't only a rural question.
Can you drink well water after a flood?
Not until it's tested. EPA's wording on its flooded private well page is direct: "Do not drink well water until it is tested. Contact your local health department." Until a lab result comes back, use stored or bottled water for drinking, cooking, brushing teeth and making baby formula.
Who tests a flooded well in Seminole and Orange counties?
Your county health department. The Florida Department of Health in Seminole County handles private well water for Seminole homes, and DOH-Orange does the same across the county line, where a coliform bacteria test costs $49. FDOH's private well page says the county office can explain how to collect the sample yourself, and to always use a state-certified laboratory.
FDOH's well disinfection handout says that if E. coli or fecal coliform shows up, the water should not be used for drinking, cooking or bathing. If your well water smells like gasoline after a flood, DOH-Seminole asks you to call its office; that's a chemical problem, not a germ problem.
What does disinfecting a well involve?
Shock chlorination with plain bleach, done carefully and followed by another test. FDOH lists a flooded well as one of the times to disinfect. Its handout walks through the steps, including disconnecting softeners and filters, switching off and draining the water heater, and leaving the chlorinated water in the pipes at least eight hours or overnight. Use FDOH's table for the bleach amount, since it depends on the well's depth and width, and retest with a certified lab before anyone drinks the water.
Some wells need a pro. FDOH says a well with its pump in a pit, a flowing well, or a sanitary seal without a threaded plug should be disinfected by a licensed well contractor or licensed pump installer. Pump wiring is for a licensed electrician; your part is the breaker. Disinfection also won't clear chemicals such as fuel or pesticides.
Should you pump a flooded septic tank?
No, not while the drainfield is flooded or saturated. EPA's after-the-flood septic page warns that pumping a tank under those conditions could cause it to try to float out of the ground and may damage the inlet and outlet pipes.
Instead, EPA says to drastically reduce water use in the house.
How do you use a septic system while the ground is still wet?
As little as possible. EPA says that when the water table is high, the only way to keep sewage from backing up into the house is to relieve pressure on the system by using it less. Hold off on full use until the water in the drainfield soil is lower than the water level around the house.
That means short showers and laundry spread over several days; EPA notes that a whole week's wash in one day can flood a drainfield. Keep vehicles and mowers off it. Our septic pumping and care page covers the everyday habits that matter once things dry out.
Flooded well and septic: do and don't
| System | Do | Don't |
|---|---|---|
| Private well | Call the county health department and get a certified lab test | Drink, cook with or brush teeth with the water before the result |
| Private well | Follow FDOH's disinfection steps, or hire a licensed well contractor | Touch pump wiring beyond the breaker |
| Septic tank | Cut water use sharply | Pump the tank while the ground is saturated |
| Drainfield | Wait until the soil drains | Drive or run equipment over it |
| Tank lid | Let a trained specialist open it | Open or climb into the tank |
What are signs the septic system was damaged?
Settling over the tank, or a system that won't accept water, are the two EPA names for flood damage; either one calls for an inspection. Other warning signs from EPA's list of failures include sewage backing up into drains, gurgling pipes, wet spots or odors over the tank or drainfield, and slow drains throughout the house. See drainfield trouble for more.
If the ground is sinking over the tank, keep people and pets off it and call a registered septic tank contractor and the county health department. EPA says only trained specialists should open or repair a tank, because tanks may contain dangerous gases. EPA also says electrical connections should be checked before power is restored; on a system with a pump or alarm, leave that to a licensed electrician or your septic contractor. For a hole that looks like more than settling, see sinkholes and pipes.
What if sewage backed up into the house?
Keep everyone out of it and avoid touching it. For cleanup, EPA's septic malfunctions page says to disinfect with a mix of 90% water and 10% household bleach, and to keep the area out of use until it has been dry for at least 24 hours.
Do you need a permit to repair a flood-damaged septic system?
Yes. Under s. 381.0065, Florida Statutes, nobody may repair or modify a septic system without a permit, and a repair permit is good for 90 days. DEP oversees the program; in Seminole and Orange counties you apply through the Florida Department of Health office in your county. DEP keeps a search tool for registered septic contractors.
Readers often ask
The flood didn't reach my house, only the yard. Do I still need to test the well?
If floodwater reached the wellhead, yes. Keep it out of glasses and cooking pots until the well is disinfected and a lab result shows it clean, and the county health department can tell you how to sample it.
Can I just pour bleach down the well and be done?
FDOH's method has several steps, a bleach amount that depends on the well's size, and a retest at a certified lab afterward. Some wells, such as those with pumps in a pit, need a licensed well contractor.
When can I have the septic tank pumped?
Not while the drainfield is flooded or saturated. EPA warns a tank pumped then can try to float out of the ground. Wait for the soil to drain, then have a registered contractor look at it.
Why are my toilets gurgling after the storm?
Gurgling is on EPA's list of septic warning signs, and a high water table can push the system to its limit. Use as little water as possible and call a registered septic contractor if it keeps up after the ground dries.
Where this came from
- EPA — What to Do With Your Private Well After a Flood — don't drink until tested; contact the health department
- EPA — Septic Systems: What to Do after the Flood — don't pump a saturated system; reduce water use; trained specialists only
- EPA — Resolving Septic System Malfunctions — warning signs; backup cleanup
- EPA — How to Care for Your Septic System — spreading laundry across the week
- Florida DOH — Well Water Facts: Well Disinfection (PDF) — when and how to disinfect; wells needing a licensed contractor
- Florida DOH — Private Well Water Testing — sampling and certified labs
- DOH-Orange — Drinking Water — test fees
- DOH-Seminole — Drinking Water Services — private well help
- Florida Statutes s. 381.0065 — septic repair permits
- FDEP — Onsite Sewage Program — septic program and statewide numbers