A slab leak is a leak in a water line that runs under or through the concrete slab your home sits on. You cannot see it, but you can usually feel it, hear it or find it on your water bill.
The earlier you catch one, the smaller the repair and the dry-out. Here are the signs, a simple test you can run today, and what happens once a plumber confirms it.
What a Slab Leak Is and Why South Florida Homes Are at Risk
Basements are rare in South Florida for a simple reason: groundwater sits close to the surface. The USGS notes that across much of the Biscayne aquifer, the top of the aquifer is at or near land surface.
So most single-family homes here are built on concrete slabs. In many of them, water supply lines run beneath or inside that slab before rising up to the sinks, tubs and appliances.
When one of those buried lines springs a leak, the water has nowhere obvious to go. It spreads under flooring, wicks into baseboards and drywall, and soaks the soil under the house.
The usual culprits:
- Corrosion in older metal supply lines.
- Abrasion where a pipe rubs against concrete or gravel as it expands and contracts with hot water.
- Poor installation, such as a kinked or nicked line set during construction.
- Pressure and movement, from high water pressure or shifting soil under the slab.
A leak on the hot side often shows up faster, because it also makes your water heater run harder. If you have had trouble there, our guide to water heater leak risks and recovery is worth a read.
Slab Leak Warning Signs Inside and Outside the House
No single clue proves a slab leak. Two or three of these together are a strong signal to test.
Inside the house:
- A warm spot on the floor, often in a hallway, kitchen or bathroom, from a leaking hot water line.
- The sound of running water when every faucet and appliance is off.
- Damp carpet, cupped wood or loose tiles with no spill nearby.
- A musty or mildew smell near baseboards.
- A water heater that seems to run constantly.
- Low water pressure that comes on without explanation.
Outside and on paper:
- A water bill that jumps with no change in your habits.
- A water meter that moves when nobody is using water.
- Wet soil or pooling along the foundation when it has not rained.
The EPA offers one rule of thumb for bills: a family of four using more than 12,000 gallons a month in the cooler months probably has a serious leak.
The Water Meter Test You Can Run Today
The EPA’s method is simple: check your water meter before and after a two-hour period when no water is being used. If the meter changes at all, you probably leak.
- Shut off every water user. Faucets, toilets, the washer, the dishwasher, the ice maker and the irrigation system.
- Read the meter. Write down the number, or note the small leak indicator if your meter has one.
- Wait two hours without running any water.
- Read it again. Any movement means water is leaving the plumbing somewhere.
- Rule out the toilets. The EPA suggests a few drops of food coloring in each tank. Color in the bowl after 10 minutes means a toilet leak, not a slab leak.
- Close the main shutoff at the house and watch the meter. If it still moves, the leak is likely in the line between the meter and the house.
Small leaks add up fast. The EPA estimates the average household’s leaks waste more than 9,300 gallons a year, and that is before any floor or wall damage.
How Plumbers Find and Fix a Slab Leak
A licensed plumber confirms the leak first, then pinpoints it before anyone touches the concrete. Pressure tests isolate whether the hot or cold side is losing water, and listening equipment or thermal imaging narrows down the spot.
Once it is located, there are three common repair paths:
| Repair | How it works | Best when | Trade-off |
| Spot repair | Break a small opening in the slab, fix the damaged section, patch the concrete | One isolated leak in otherwise sound pipe | Flooring in that spot gets torn up |
| Reroute | Abandon the buried line and run a new one through walls or the attic | Older pipe with more leaks likely | Drywall openings to patch and paint |
| Full repipe | Replace the home’s supply lines | Repeat leaks or widespread corrosion | Highest upfront cost |
Ask your plumber which option fits the age and condition of your pipes. Fixing one spot in a line that is failing everywhere often leads to the next leak a few feet away.
If the leak broke loose suddenly and water is spreading, emergency burst pipe repair in South Florida can stop the flow while the long-term fix gets planned.
What Happens After the Repair: Drying Out and Insurance
Fixing the pipe stops new water. It does nothing about the water already in your floors and walls, and that is where most of the long-term damage happens.
The EPA says wet materials should be dried within 24 to 48 hours to prevent mold growth. Water under tile, laminate and baseboards will not dry that fast on its own.
A proper dry-out usually means:
- Mapping the wet area with moisture meters, room by room.
- Pulling baseboards and wet padding, and opening drywall where water wicked up.
- Running air movers and dehumidifiers, a process called professional structural drying, until readings hit dry standards.
- Checking behind cabinets and walls for growth, since mold behind drywall often shows no sign on the painted side.
On insurance, coverage for slab leaks varies widely by policy. Some pay to access the leak and repair the resulting damage but not the pipe itself, so read your policy or ask your agent.
Timing matters too. Many Florida policies exclude constant or repeated leakage over 14 days or more, according to Marshall Dennehey. Report the leak as soon as you confirm it, and keep Florida’s 1-year insurance claim deadline in mind.
When to Call a Restoration Pro
Your plumber fixes the pipe. A restoration team handles everything the water touched. Bring one in when:
- Flooring is cupped, lifting, or soft over a wide area.
- Baseboards or the bottom of the drywall feel damp or look stained.
- You smell mildew in rooms near the leak.
- The leak may have run for weeks before anyone noticed.
Slab water spreads sideways in ways that surprise people. Our look at why water damage spreads fast in Fort Lauderdale homes explains what is happening under the floor.
Slab leak confirmed? BuildEase by Florida Mitigation Group dries it out right. Our IICRC-certified team serves Broward and Palm Beach 24/7, starting with a free inspection and a written Finding Report.
Slab Leak FAQs
What are the first warning signs of a slab leak?
The most common are a warm spot on the floor, the sound of running water with everything off, and a water bill that jumps for no reason.
How can I test for a slab leak myself?
Use the EPA meter test. Shut off all water use, read the meter, wait two hours, and read it again. Any change points to a leak.
Is a slab leak an emergency?
A small, slow leak is not usually a same-hour emergency, but it should be confirmed within days. The longer it runs, the more flooring, drywall, and soil it soaks.
Does homeowners insurance cover slab leaks in Florida?
It depends on your policy. Some cover access and resulting damage but not the pipe repair, and many exclude leaks that ran 14 days or more.
Who do I call first, a plumber or a restoration company?
Call a licensed plumber to find and fix the leak. Call a restoration company as soon as you see wet flooring or walls, ideally the same day.
How long does drying take after a slab leak?
Most jobs run several days, depending on how far the water spread and what the floors are made of.
