Slab Leak Signs in South Florida Homes and What to Do First

Most single-family homes in South Florida sit on a concrete slab poured right on the ground. Basements are rare here and crawl spaces are uncommon, so in many homes the water lines and drain lines run under or through that slab. When one of those pipes starts leaking, the water has nowhere obvious to go. It soaks into the soil and the concrete, and it can run for weeks before anyone notices.

Here are the warning signs, why older homes in Broward and Miami-Dade tend to get them, the checks you can do yourself, and how a plumber finds the leak.

Common signs of a slab leak

A slab leak rarely shows up as a puddle in the middle of the floor. The clues are usually small and easy to explain away. Watch for:

• A water bill that jumps when nothing about how your household uses water has changed.
• The sound of running water when every faucet, toilet and appliance is off.
• Warm or hot spots on the floor, often noticed barefoot on tile. This usually points to a leak on a hot water line.
• Damp or discolored flooring, carpet that feels wet near a wall, or wood and laminate that starts to cup or lift.
• A musty smell or mildew along baseboards with no obvious source.
• Lower water pressure at several fixtures at once.
• A water heater that seems to run all the time, because it keeps reheating water that is leaking away.
• New cracks in tile or along the bottom of walls. Cracks have many causes, so treat this as a reason to check, not proof of a leak.

One sign on its own isn't a diagnosis. Two or three together, especially a high bill plus a warm spot or the sound of water, are worth checking right away.

Why older South Florida slab homes get them

Many older homes in our area have copper water lines buried under or set into the slab, where conditions are hard on pipe.

Age and wear

After decades in service, pipe walls can thin and develop small pinhole leaks. Water chemistry, water velocity and the overall age of the system all play a part.

Movement and rubbing

Hot water lines expand slightly every time they heat up and shrink again when they cool. Where a pipe touches concrete, gravel or another pipe, that small, repeated movement can wear through the pipe wall over the years. It's one reason a warm spot on the floor is such a common clue.

Settling

The soil under a slab can shift and settle over time, which puts stress on the pipes and fittings below the floor.

Drain lines can leak too

Not every slab leak is on the water supply side. Many older homes also have cast iron drain pipes under the slab, and cast iron can corrode and crack from the inside after many years. A drain leak won't show up on your water meter, because drain pipes aren't under pressure. It's more likely to show up as sewer odors, slow drains or damp spots near bathrooms. A camera inspection of the drain lines is the usual way to check those.

What to do first

1. Run the water meter test

Your water meter is the simplest leak detector you have. It's usually in a ground box near the street or sidewalk.

1. Turn off every faucet and water-using appliance in the house, including the dishwasher, washing machine, ice maker and irrigation system. Make sure no toilet is refilling.
2. Open the meter box lid and look at the dial. Many meters have a small triangle, star or wheel that spins when even a trickle of water is flowing. Digital meters may show a flow reading instead.
3. If that indicator is moving, or the reading changes over an hour or so with nothing running, water is going somewhere.

Before you assume the worst, rule out the toilets. A worn flapper can let water trickle from the tank into the bowl without making much noise. Put a few drops of food coloring in each tank, wait about 15 minutes without flushing, and see whether color shows up in the bowl.

2. Narrow it down with your main shut-off

Find the main shut-off valve for the house. It's often where the water line enters the home, on an outside wall, in the garage, or near the water heater. Close it, then check the meter again.

• If the meter stops, the leak is somewhere inside the house.
• If it keeps moving, the leak is more likely between the meter and the house, on the main service line or an irrigation line.

3. Limit the damage while you wait

If you've confirmed a leak inside the house, keep the main valve closed except when you need water. If your clue is a warm spot on the floor, the leak is probably on the hot side. Closing the cold water valve at the top of the water heater stops water from feeding the hot lines, while the cold side stays on for toilets and drinking water. If you have an electric water heater and close that valve, switch off its breaker too as a precaution.

Move rugs and furniture off any damp areas and take photos. Homeowners policies handle slab leaks in different ways, so call your insurance company early and ask what they need from you.

How electronic leak detection works

The goal with modern electronic leak detection is to pinpoint the leak before the floor is opened, so only a small section has to come up. Depending on the home, a technician may use several tools together:

• Pressure testing. Isolating the hot and cold sides of the plumbing and watching for pressure loss confirms which line is leaking.
• Acoustic listening equipment. Water escaping a pressurized pipe makes a sound. Sensitive ground microphones let a technician listen through the floor and find where that sound is strongest.
• Line tracing. Electronic locators map where the pipes actually run under the slab, which is often not where you'd expect.
• Thermal imaging. On hot water leaks, an infrared camera can show heat spreading through the floor around the leak.

Repair options once the leak is found

There are two common approaches, and the right one depends on your home.

• Spot repair. Open a small section of the slab at the leak, repair the pipe and patch the concrete. This makes sense when the rest of the piping is in good condition.
• Reroute. Leave the leaking line in place, take it out of service, and run a new line through the walls or attic instead. This is often considered when a home has already had more than one slab leak, because it gets the water line out of the slab entirely.

The age of the piping, where the leak is, and what sits on top of it all affect the choice. A good plumber will walk you through both options before you decide.

Get it checked before it gets worse

A slab leak doesn't fix itself, and the longer it runs, the more water ends up under your floor. If you're seeing any of these signs, call Father & Son Plumbing at (786) 922-5974. We're a family-owned, licensed and insured plumbing company (Florida license CFC1433358) serving South Florida since 2008 from our bases in Hallandale Beach and Aventura. We're open Monday through Friday and Sunday, 8 AM to 5 PM (closed Saturday), with same-day appointments when the schedule allows. The $49 service call is waived when you go ahead with the repair, and you'll get a written price before any work starts.