Slab Leak Repair in St. George, UT

What a slab leak is

Most homes in St. George and the surrounding towns are built on concrete slab foundations. The water supply lines that feed kitchens, bathrooms and the water heater often run under that slab or are embedded in it. A slab leak is any leak in one of those buried lines. Because the water goes into the soil and gravel beneath the concrete instead of onto a floor you can see, a slab leak can run for weeks or months before anyone notices. That is why it pays to know the signs and to check early. Drain and sewer lines can leak under a slab too, but most slab leak calls involve pressurized supply pipe, which keeps losing water as long as the leak is open.

Signs of a slab leak

• A warm or hot spot on the floor. A leaking hot-water line heats the concrete above it. Bare feet often find it first, on tile near a kitchen, bathroom or the path toward the water heater.
• Running water you can hear with every fixture, the irrigation and the ice maker off.
• A water meter that keeps moving when nothing is on. This is the most reliable at-home check (see below).
• A higher water bill without any change in how you use water.
• A water heater that runs more than it used to, because it keeps refilling and reheating water that is leaking away.
• Damp carpet, cupping wood or lifting vinyl, a musty smell along a baseboard, or new mildew where there was none.
• New cracks in tile or the slab, or a damp spot outside next to the foundation.
• Low pressure at some fixtures that came on gradually.

One sign alone can have other causes. A warm floor can come from a duct, and a high bill can come from an irrigation leak. Two or three signs together are a strong reason to check the meter today.

Check the meter first

The City of St. George recommends turning off all water inside and outside the home, including washers, ice makers and irrigation, and then watching the water meter, which is usually in a box near the property line or in the driveway. If it is still turning, there is a leak somewhere (City of St. George Water Services, Collection and Distribution (FAQ)). Most meters have a small leak indicator, often a triangle or star, that spins with even a slow drip.

1. Everything off, including the sprinkler controller.
2. Read the meter and write down the number, or take a photo.
3. Close the main shut-off at the house. If the meter stops, the leak is inside the house, and a slab leak is one possibility. If it keeps moving, the leak is more likely in the service line between the meter and the house or in irrigation tied in before the house valve.
4. Wait an hour with no water used and read it again if the indicator is hard to see.

Our guide to finding your shut-off and checking for leaks has more detail. The line on the house side of the meter is the property owner's responsibility; the city handles the meter and the main.

What to do right now

• If you can see water coming up or the floor is getting wet, close the main shut-off. Keep people away from standing water near outlets and appliances.
• If you suspect a hot-water leak, closing the cold-water valve on top of the water heater stops water feeding the hot side. For a gas heater, set it to vacation or pilot so it is not firing on an empty or leaking system; for an electric heater, switch off its breaker.
• Write down meter readings and take photos of warm spots, damp flooring and cracks. They help with diagnosis and with any insurance claim.
• Call your homeowner's insurer early if there is water damage. Policies differ a lot on whether they pay to find and access the leak, repair the pipe, or only repair resulting damage, so ask before work starts.
• Do not start breaking concrete to look for it. A leak under a slab can surface feet away from where the pipe actually failed.

How a slab leak is located

Good leak location keeps the repair small. The usual sequence:

1. Isolate the system. Testing the hot and cold sides separately, and sometimes individual branches, shows which line is losing water.
2. Pressure test. Gauges confirm that a section is losing pressure and roughly how fast.
3. Listen. Acoustic ground microphones pick up the sound of water escaping under concrete. The noise is loudest near the break.
4. Look for heat. On hot-water leaks, thermal imaging can show the warm line and the spot where heat spreads out.
5. Trace the line. Line-tracing equipment maps where the pipe actually runs, which matters in homes that have been remodeled.
6. Mark and confirm the most likely spot before any flooring or concrete is opened.

Repair options: direct access, reroute or repipe

Direct access (spot repair)

The floor covering is pulled back at the marked spot, a section of slab is cut out, the soil is dug down to the pipe, and the damaged section is repaired. Then the hole is backfilled and the concrete patched. This can make sense when there is a single leak in pipe that is otherwise in good shape and the spot is reachable. Downsides: dust and noise, flooring that has to be replaced or blended in, and pipe that may leak again somewhere else under the same slab.

Reroute

The leaking line is abandoned under the slab, and a new line is run through walls, ceilings or the attic to the same fixtures. Rerouting avoids breaking the floor, replaces the whole problem run rather than one spot, and leaves the new pipe where it can be reached later. It does mean some drywall openings and patching. In attics that get very hot in a St. George summer, new lines need to be insulated and routed sensibly so the cold water does not run warm.

Repipe

When a home has had more than one slab leak, or the pipe is an older material that is failing in several places, replacing the supply piping for the whole house, usually overhead, can make more sense than chasing leaks one at a time. See repiping and water pressure for how that works.

Epoxy lining

Some companies offer epoxy pipe lining for slab leaks. It can work on some lines, but ask about the pipe material and condition, how the lining is tested, and what happens if the line leaks again.

The right choice depends on where the leak is, what the pipe is made of, the age of the home, how many leaks there have been and what is on the floor above it. Ask for the reasons behind any recommendation, and what the floor or walls will look like afterward.

Why slab leaks happen in Southern Utah homes

A few local conditions add stress to buried pipe. These are general factors, not a diagnosis of any one house:

• Problem soils. The Utah Geological Survey identifies expansive soil and rock as the most troublesome construction condition in the St. George-Hurricane area, and also maps collapsible and gypsum-bearing soils (Utah Geological Survey, Geologic-Hazard Maps for the St. George-Hurricane Area; Utah Geological Survey, Problem Soil and Rock). Soil that swells, shrinks or settles can move a slab and stress the pipe joints under it.
• Hard water and water chemistry. The city's water quality report suggests softener settings of 13 to 24 grains per gallon, which tells you how mineral-heavy the water is (City of St. George, 2024 Drinking Water Quality Report). Scale, water chemistry and high water pressure can all contribute to wear on copper and fittings over time.
• Abrasion and movement. Copper laid in contact with gravel or rebar, or pipe that expands and contracts with every hot-water draw, can wear through where it rubs.
• Older materials and older homes. Homes built or remodeled in earlier decades may have materials that are near the end of their life. Repeat pinhole leaks are a sign the rest of the pipe may be wearing too.
• High pressure. Some parts of the area see high water pressure. A failed or missing pressure-reducing valve puts extra stress on every joint in the house.

How long can a slab leak wait?

Not long. Water running under a slab is lost water you pay for, and the EPA notes that household leaks can waste thousands of gallons a year in a typical home (EPA WaterSense, Statistics and Facts). Over time it can soften the soil under the foundation, damage flooring and baseboards and lead to mold. A small leak found early usually means a smaller, simpler repair.

Get a free slab leak quote

Use the free quote form. It helps to include the age of the house, what signs you have noticed, whether the meter moves with everything off, whether a floor spot feels warm, and whether you have had a slab leak before. We'll call you back to talk it through. For leaks you can see, such as toilets, faucets, supply lines and irrigation, see leak detection and repair.

Sources: City of St. George Water Services, Collection and Distribution (FAQ); Utah Geological Survey, Geologic-Hazard Maps for the St. George-Hurricane Area; Utah Geological Survey, Problem Soil and Rock; City of St. George, 2024 Drinking Water Quality Report; EPA WaterSense, Statistics and Facts.