On older platted lots, a septic drain field sits in sandy soil with a water table that can rise close to the surface. After heavy rain the field cannot absorb more liquid, so wastewater backs up to the lowest drains inside the house. It is Category 3 water, and the tank and field are fixed by a septic contractor.
Key takeaways
- About 17,380 homes in the city and its service area remain on septic, and many sit on lots platted by the General Development Corporation beginning in 1958 and sold mostly by mail.
- A septic system sends wastewater to a tank and then to a drain field, which needs unsaturated soil to work; when rain fills the soil or the water table rises, the field stops accepting liquid and the system backs up.
- The first sign is usually slow drains, gurgling and wastewater at the lowest fixture, such as a shower, tub or floor drain, rather than an outdoor smell.
- Septic backup water is Category 3, so carpet, pad, baseboards and wet drywall generally come out, and hard surfaces are cleaned and disinfected before structural drying.
- A restoration crew cleans and dries the inside of the house; pumping the tank or repairing the drain field is a septic contractor's job and is not part of this service.
Why do septic systems back up in older Port St. Lucie lots?
Older lots often rely on a tank and a drain field in sandy soil with a high water table. Heavy rain saturates that soil, the field cannot take any more liquid, and wastewater has nowhere to go except back up the pipe to the lowest fixtures in the house.
A septic system has three jobs. The tank holds wastewater long enough for solids to settle, the outlet sends the liquid to a drain field of buried pipes, and the soil around those pipes treats and absorbs it. The last step needs air in the soil. When rain fills the soil with water, or a high water table rises to meet the pipes, there is no room left for the liquid.
The sandy soil and flat terrain of this coast drain quickly in dry weather, so nothing looks wrong for months. Problems show when a wet spell, a wet season or a run of tropical rain pushes the water table up. Port St. Lucie receives roughly 53.5 inches of rain a year on the Fort Pierce normals, about two thirds of it from May to October, so the stress arrives in the same months each year.
Many older lots also carry other pressures: a tank that has not been pumped in years, roots in the field, or a field that was sized for a smaller household. This page cannot tell you which applies to your lot, and a septic contractor can inspect the tank and field.
Heavy rain is also not the only trigger. A household that suddenly uses more water, such as a long run of guests, a plumbing leak that feeds the tank, or several loads of laundry in a day, can overload a system that was already close to its limit. Spreading out water use is a sensible habit on any septic lot, and especially in the wet season.
How did so many older lots end up on septic?
The General Development Corporation bought River Park and about 40,000 acres along the North Fork of the St. Lucie River in 1958 and sold quarter-acre lots, mostly by mail, before most had houses. Lots were built on septic first. The city took over water and sewer in 1994 and requires new buildings to connect.
That platting is the old Port St. Lucie of the 1960s and 1970s. Many of those homes are single-storey concrete-block-and-stucco houses on slabs, with canals nearby and, in some cases, septic and wells. Construction type is a general pattern of the era, and each home needs checking on its own.
The city utility took over water and sewer service in 1994, and about 17,380 homes in the city and its service area remain on septic. Whether your home is one of them is a matter of your property records and the city utility, not of the age of the house alone. If you are unsure, ask the city before you assume either way.
Newer parts of the city, including St. Lucie West, Tradition, Southbend Lakes and the Becker Road corridor, are on city utilities, so a sewer backup there is a different problem with a different source. The sewage cleanup page covers that side.
A practical way to find out is to read the closing paperwork or ask the city utility, because a listing description or a neighbour is not a reliable answer for a specific lot. Knowing which system your house uses decides who you call first, and it also shapes how you read your insurance policy.
What are the signs a septic system is backing up?
Slow drains in several fixtures, gurgling pipes, toilets that will not flush properly, and wastewater at the lowest drain are the usual signs. Soggy, sour-smelling ground over the drain field or tank can appear first. Several fixtures acting up at once points to the system rather than a single clogged pipe.
A single slow sink is usually a local clog. When the shower, the tub, the washing machine drain and a toilet all slow down together, the problem sits downstream of all of them. Water or sewage may rise first in the lowest fixture, because it sits closest to the level the wastewater has reached in the line.
The table below sorts the signs by where they appear and what to do first. It is general guidance, and a septic contractor decides what is happening to the tank and field.
| What you notice | What it can mean | First step |
|---|---|---|
| Slow drains in many fixtures | Tank full or drain field saturated | Reduce water use and call a septic contractor |
| Gurgling in pipes, toilets that bubble | Air trapped by a blocked or saturated system | Stop flushing and running water |
| Wastewater in a tub, shower or floor drain | Backup has reached the lowest fixture | Stop all water use, keep people out, call for cleanup |
| Wet, sour ground over the field | Field not absorbing liquid | Keep people and pets off the area; call a septic contractor |
| Backup only after heavy rain | High water table or flooded field | Note the dates and rainfall; tell the contractor |
What should I do first when wastewater is coming into the house?
Stop using water: no flushing, no laundry, no dishwasher, no showers. Keep people and pets out of the wet area and do not touch the water with bare hands. Call a septic contractor for the tank and field, and a restoration crew for the cleanup and drying inside.
Every gallon you run goes into the same system, so turning off water use is the single most useful thing you can do. If the water is still rising, shut the water at the main valve if you can do so safely. Do not stand in the wet area near outlets, and switch power off to that area only if the panel is dry and safe to reach.
Wear gloves and boots if you must enter, and wash well afterwards. Do not mop or wet-vacuum sewage with household equipment, because it spreads contamination and the equipment is hard to clean. Photograph the affected floors, the drains and the yard before anything is moved, as you may want those pictures for your insurer later.
Call a septic contractor for the system and call (833) 490-5225 when you want a crew dispatched as fast as one is available to remove the water, clean the surfaces and start drying. The septic backup water damage page describes what happens inside.
What does the cleanup inside the house involve?
Crews remove standing wastewater, take out porous materials that cannot be cleaned, clean and disinfect hard surfaces, then dry the structure with air movers and dehumidifiers and re-check readings until dry. Because septic water is Category 3, carpet, pad and wet drywall usually go rather than being saved.
Category 3 means the water is grossly contaminated. Under IICRC S500 terms, sewage and similar water are not safe to dry in place, since porous materials soak up contamination that surface cleaning cannot reach. That is why a stained carpet and pad are usually removed and why drywall may be cut out above the water line.
On a slab home, wastewater can spread across the whole floor plan and wick into the bottom of block-and-stucco walls and cabinet bases. A crew uses moisture meters and thermal imaging to find where it went, then dries until readings are normal. The honest urgency here is that fast drying limits mold, and mold can still have grown before the work started.
This work is not tank pumping or drain-field repair. Those belong to a septic contractor, and cleanup inside a house will not stop a second backup if the field is still saturated. If the system cannot be fixed immediately, ask the contractor and the crew how to avoid repeating the loss.
Older homes may contain asbestos or lead-bearing materials. Homes built before the 1980s may contain asbestos materials, and pre-1978 homes fall under the EPA lead rule for renovation. If cleanup or demolition will disturb old flooring, joint compound or paint, say so before work starts.
Who pays, and does insurance cover a septic backup?
A homeowners policy usually does not cover sewer or drain backup unless an endorsement was added, and flood is a separate policy. Septic system repair is typically a maintenance cost. Coverage is decided by your insurer under your own policy, so read the water-backup wording and ask your agent.
Coverage language for backups varies, so check whether your policy has a water or sewer backup endorsement and what its limits are. If a flood event was involved, flood coverage is separate and typically carries a waiting period of about 30 days, as covered in flood versus homeowners insurance for water damage in Florida.
The crew can document the damage for your claim with photos and moisture readings, but coverage is not decided by the crew. The emergency-stage price is explained and approved before work starts, and repairs after drying, such as new flooring, are quoted separately.
Before any rebuilding, note the permit rule that applies to your address: repairs in the city go through the City of Port St. Lucie Building Department, unincorporated areas use St. Lucie County, and rebuilding after water damage generally needs a Florida-licensed contractor, which you can look up on DBPR's licence search.
Frequently asked questions
Can heavy rain alone cause a septic backup?
It can. When rain saturates the soil or lifts the water table, the drain field cannot absorb more liquid and wastewater can back up into the house. An undersized field, an unpumped tank or root damage make it more likely, but a septic contractor has to inspect the system.
Is it safe to stay in the house during a septic backup?
Usually it is better to stay out of the wet rooms and not use the plumbing. Keep children and pets away from the affected area, use a bathroom elsewhere if you can, and avoid touching the water. Staying elsewhere is sensible for a larger backup.
Will the crew pump my tank or fix the drain field?
No. A restoration crew cleans and dries the inside of the home. Pumping the tank, inspecting the field and repairing either belong to a septic contractor, and the two jobs are usually done separately, one after the other.
How do I know if my home is on septic or sewer?
Check your utility bill for a sewer charge, ask the city utility, or look for a tank lid or drain field in the yard. The city took over the utility in 1994 and requires new buildings to connect, but older homes may remain on septic.
Can I clean up a small septic backup myself?
A very small spill on a hard floor can be cleaned with proper gloves, disinfectant and ventilation, but wastewater that reached carpet, baseboards or drywall is harder to clean completely. If you are unsure how far it went, a moisture reading helps.
Sources
- U.S. EPA – Septic Systems (OnSite Wastewater Treatment)
- U.S. EPA – Mold Cleanup in Your Home
- FEMA – National Flood Insurance Program
This guide is general information for St. Lucie County homeowners, not a substitute for an on-site inspection. Prices are estimates. See our disclaimer.