A septic system depends on soil to absorb the liquid that leaves the tank. After several days of rain the ground around the drain field is saturated, so the liquid has nowhere to go and backs up into the house, usually first at the lowest drain. Stop using water, shut off the flow, and call the people who handle the tank and the people who handle the wet floor.
Key takeaways
- A septic drain field works by letting liquid soak into soil, so saturated ground stops it from working.
- The lowest drain in the house is usually the first to show a backup, because the wastewater meets the blockage there first.
- Stop running water as soon as you see a backup, and keep people and pets out of standing water near outlets.
- Pumping the tank and repairing the drain field are separate jobs from cleaning up water and waste inside the home.
- Florida licenses mold assessors and remediators separately, and mold work above about 10 square feet falls under those rules.
- Standard homeowners policies often exclude sewer and drain backup unless an endorsement was added, so check your policy.
Why does a septic system back up after several days of rain?
A septic system separates solids in a tank and sends the liquid to a drain field, where the soil absorbs it. Rain that keeps falling fills the soil until it cannot take in any more liquid. When that happens, the system pushes back toward the house.
In Polk County the rain comes in a steady pattern. The National Weather Service puts the rainy season for west central Florida at roughly 25 May to 10 October, and 55 to 70 percent of the annual rain typically falls from June through September. A single heavy afternoon storm may drain away, but several days of rain in a row give the ground no time to recover between storms.
A septic system is designed to work in unsaturated soil. The liquid leaving the tank passes through the drain field and into the ground, and the soil does the final treatment. When the ground is already full of water, the drain field cannot accept the liquid, and the system has no other exit except back up the pipes.
What happens to the drain field when the ground is saturated?
Saturated soil stops absorbing water, so the drain field is effectively full even when the tank is working. The water table can rise close to the surface after days of rain, which leaves the field with little dry soil to use.
The drain field is a buried area, so most homeowners never see it. What they see is what happens inside the house. Toilets gurgle, drains run slowly, and water appears where it should not. Those signs usually mean the field is saturated and the system is pushing water back, not that the tank has failed.
Lakeland had 9,183 households on septic, according to a local news outlet's report of the city's water compliance manager, who counted homes in the service area that pay for electricity but not wastewater service. Across the county, well over a hundred thousand households depend on onsite systems. A saturated drain field affects every one of those homes at once after a wet week, so a backup on one street is often a sign that the whole area is wet.
Which fixture backs up first, and what should I do with it?
The lowest drain in the house usually shows the backup first, such as a floor drain, a shower or a toilet on the lowest level of the home. Stop using all water at once, then shut off the flow to the house if you can do it safely.
Wastewater takes the easiest route, and the lowest drain is where it reaches the pipes first when the line is blocked or the system is full. Water may rise in a shower or a floor drain before a toilet or sink shows any sign. If you see water coming up at the lowest point, treat it as a backup and not as a clog you can plunge.
Do not run the washing machine, dishwasher or shower. Keep children and pets out of the water, and do not step into standing water near outlets, switches or appliances. If the electrical panel is dry and safe to reach, turn the power off to the affected area. If it is not, leave the panel alone and call for help. Take photos of the water and the fixture before anything is moved, because your insurer will want them.
How do I tell whether the problem is the tank or the house?
The tank and drain field belong to the system and are inspected and permitted by the Florida Department of Health in Polk County. The water and waste inside the home belong to cleanup. Two different people usually handle each part.
The Florida Department of Health in Polk County runs the onsite sewage program, which inspects, evaluates and permits septic systems in the county. If you are not sure whether your system is failing, that office is the right place to ask about the system itself. A septic pumping company handles emptying the tank, and drain-field repair is separate work again. Neither of those is something a water-damage crew does.
Cleanup begins once the water is inside the house. A restoration crew can stop the water from spreading, remove what is wet and bring the building back toward dry. Keep the two roles separate in your head. A pumper can empty the tank, but the floors, walls and contents still need drying, and a restoration crew does not pump tanks.
What does the cleanup inside the house involve?
Sewage-contaminated water is the most serious category of wet damage, so it is removed quickly and the affected materials are handled with care. Drying follows, and the crew re-checks readings until the materials are dry.
Standard practice starts with moisture meters and thermal imaging to find water that has soaked under flooring, behind baseboards and into wall cavities. Materials that cannot be cleaned and dried safely are removed. Air movers and dehumidifiers then pull moisture out of the structure, and the crew re-checks the readings until the materials reach a dry state. Photos and readings can be shared with your insurer.
Speed matters because mold can start in damp materials quickly. The EPA advises keeping indoor humidity below 60 percent relative humidity, ideally between 30 and 50 percent, and drying a wet area within 24 to 48 hours where possible. Those are targets, not guarantees, but they are the honest reason to start drying early. Call (833) 490-5225 to reach a crew at any hour; phones are answered 24/7, and a crew is dispatched as fast as one is available.
Does insurance cover a septic backup?
Homeowners policies often exclude sewer and drain backup unless an endorsement was added, so coverage depends on your own policy. Check it before assuming anything.
A homeowners policy often covers sudden and accidental water damage, such as a burst pipe, but usually does not cover sewer and drain backup or flooding unless an endorsement was added. Flood insurance is a separate policy. Coverage is decided by your insurer under your own policy, so the first step is to read the endorsements and ask your agent what applies.
Take photos before anything is moved, stop the water if you can do so safely, and call your insurer early. A restoration crew can document the damage with moisture readings and photos for your claim, but the crew does not decide what is covered.
When does Florida's mold licensing come into a septic cleanup?
Florida licenses mold assessors and remediators through the Department of Business and Professional Regulation, and mold work above about 10 square feet falls under those rules. A person who assesses mold may not remediate the same structure in the following 12 months.
Mold is a common follow-up when a septic backup is not dried quickly. Florida's licensing rules for mold apply to areas above about 10 square feet. Mold can trigger allergy and asthma symptoms in some people. Ask any company for its DBPR license number, and look it up on DBPR's website before you agree to work.
The most useful rule for a homeowner is the separation between testing and cleanup. Under Florida law, an assessor may not remediate a structure it assessed in the previous 12 months, and a remediator may not assess one it remediated in that period. The person who tests the house should not be the person who sells the cleanup.
Why does this matter most from late spring through October?
The rainy season in west central Florida runs from about late May to early October, and most of the year's rain falls in June through September. That is the stretch when saturated drain fields and backups are most likely.
The hurricane season runs from 1 June to 30 November, with the climatological peak around 10 September. Storms that arrive in that window often bring several days of rain, and those are the days when a drain field has no chance to dry out. Flooding from lakes and stormwater can add to the problem, because water that rises around the property also saturates the ground near the field.
Known dry periods are the best time to check the system and talk to the county. In the rainy months, plan for the possibility of a backup, keep the number for a restoration crew handy, and know which fixture is lowest in your house. Sinkhole records in the county can include failed septic systems, so a sunken or soggy patch over the tank or field is worth reporting to the health department.
Frequently asked questions
Why does my toilet gurgle after it rains for several days?
Gurgling often means air is being pushed through the drain line because the drain field is full. Saturated soil cannot take in more liquid, so the system pushes back toward the house. Stop using water and watch for water rising in the lowest drain. Call the health department about the system and a restoration crew about the water.
Which drain backs up first in a single-story house?
The lowest drain in the house usually shows the backup first, such as a floor drain, a shower or a toilet on the lowest level. Wastewater meets the blockage there before it reaches higher fixtures. If water comes up at the lowest drain, treat it as a backup and stop all water use right away. Keep people and pets out of the water until it is cleared.
Who do I call for the tank and who do I call for the water in my house?
The Florida Department of Health in Polk County handles the onsite sewage program, including inspection and permitting of septic systems. A septic pumping company empties the tank, and drain-field repair is separate work. A restoration crew handles water and waste inside the home, including drying and documentation for your insurer. Keep those roles separate when you call.
Is sewage water treated differently from clean water?
Yes. Sewage-contaminated water is treated as the most serious category of wet damage, so materials are handled with more care. Standing water near outlets is dangerous, so turn off power to the area only if the panel is dry and safe to reach. Drying still follows removal, and the crew re-checks readings until the materials are dry.
Will my homeowners insurance pay for a septic backup?
That depends on your policy. Homeowners policies often exclude sewer and drain backup unless an endorsement was added, and flood is a separate policy. Read your declarations and endorsements, and ask your agent what applies. Take photos before anything is moved and call your insurer early.
Does mold from a backup need a licensed professional?
In Florida, mold remediation above about 10 square feet is a licensed activity under DBPR rules. Mold can trigger allergy and asthma symptoms in some people, so take it seriously. Ask any company for its DBPR license number and check it on DBPR's website. The person who assesses the mold should not be the one who remediates the same structure within the following 12 months.
Sources
- U.S. Environmental Protection Agency
- National Weather Service Tampa Bay
- National Weather Service
- Florida Department of Health in Polk County
This guide is general information for Polk County homeowners, not a substitute for an on-site inspection. Prices are estimates. See our disclaimer.