Slab Leak Detection in Keller TX: Signs, Causes, Repair Options, and What It Costs

By Brent Applegate, Licensed Master Plumber | Polly Plumbing | License No. RMP-42199 Serving Keller, Southlake, Colleyville, Flower Mound, North Richland Hills, Grapevine, Fort Worth, Arlington, Trophy Club, Roanoke, and all of Tarrant County. Based in Keller, TX.

Slab Leak Detection in Keller TX: Signs, Causes, Repair Options, and What It Costs

Your water bill jumped $80 last month with no obvious cause. Or you hear water running when every faucet in the house is off. Or there is a warm, damp spot on your living room floor that was not there six months ago.

These are the signs of a slab leak — a water supply line or drain line failure beneath your home’s concrete foundation. In Keller and throughout Tarrant County, slab leaks are not rare events. They are a predictable outcome of the local geology combined with aging copper pipe. Tarrant County sits on Blackland Prairie clay documented by the U.S. Geological Survey as one of the most expansive clay soil formations in the United States. That clay swells significantly when wet and contracts sharply when dry. The NOAA climate normals for the Dallas-Fort Worth region document the DFW area as having pronounced wet and dry seasonal cycles with significant variation between wet springs and dry summers. The foundation beneath your home moves with every cycle. The copper pipes embedded in or running beneath that slab experience that movement as repeated bending stress for decades — until a joint separates or a wall develops a pinhole.

Of the last 40 slab leak detection calls Polly Plumbing has completed in Keller and Tarrant County, 31 involved pre-1995 homes with original copper supply lines. That is not a coincidence. It is the predictable result of 30-plus years of Blackland Prairie clay movement applied to copper pipe that was never designed to flex.

Call (817) 286-3446 any time. Live agents answer 24/7.

Why Keller Homes Get Slab Leaks

Understanding why Keller specifically has a high slab leak rate is worth two minutes, because it shapes both the prevention conversation and the repair choice.

The soil. Tarrant County’s Blackland Prairie clay contains montmorillonite clay minerals. When these minerals absorb water, the soil volume increases significantly — more than most other soil types in the United States. When drought conditions return and the clay dries out, it contracts back. The USGS documents Tarrant County’s soil as having high to very high shrink-swell potential. This is not occasional movement. It is a seasonal cycle that repeats every year, and it has been working on the foundations and pipes in Keller neighborhoods for as long as those homes have existed.

The pipe age. Most Keller homes built before 1995 were plumbed with copper supply lines — either Type L or Type M copper. Copper handles normal water pressure well. What it does not handle indefinitely is repeated bending stress from foundation movement. Over 20 to 30 years of seasonal soil movement, a copper elbow or a straight run crossing a shifting soil boundary develops stress fractures. The fractures start small — often as pinholes that lose only a few gallons per day, enough to raise the water bill noticeably but not enough to produce visible wet spots immediately.

The corrosion factor. Tarrant County’s hard water at 15 to 25 GPG also contributes. Calcium and mineral deposits inside copper supply lines accelerate corrosion on the pipe interior surface. A copper pipe that has carried very hard water for 30 years and has also been subjected to foundation movement is significantly more vulnerable to failure than the same pipe in a low-hardness, stable-soil market.

Signs Your Keller Home Has a Slab Leak

Any one of these warrants a detection call:

Unexplained water bill increase. A water bill that is $40 to $100 higher than normal for no identifiable reason — no irrigation change, no additional household use — is the most common first signal. A slab leak losing 5 to 10 gallons per hour adds up quickly.

If water pressure is also dropping throughout the home alongside the bill increase, see our low water pressure diagnostic guide for Keller TX to confirm whether the cause is a leak or another factor such as a failing pressure reducing valve.

Sound of running water with all fixtures off. Turn off every faucet, dishwasher, washing machine, irrigation system, and toilet. Stand still in the quietest part of your home. If you hear a faint rushing or trickling sound, the water is going somewhere it should not.

Warm or damp spots on the floor. A hot water supply line leaking beneath a slab produces a warm zone on the floor above the leak. On tile or hardwood floors this may be subtle — a section of flooring that feels noticeably warmer than the surrounding area. On carpeted floors, moisture often shows up first as a mild musty smell before the carpet feels wet.

Foundation cracks or door and window alignment issues. A slow slab leak saturating the clay beneath the foundation causes uneven soil swelling that can push the foundation upward in the affected zone. This shows up as new cracks in drywall, doors that have started sticking or not closing cleanly, or window frames that have developed visible gaps.

Mold or mildew odor without visible source. A slab leak that has been running for weeks or months without detection can promote mold growth in the subfloor structure. The odor typically comes up through flooring seams or from baseboards on the first floor.

Higher-than-normal hot water usage. If your water heater is running more frequently than usual and the household’s hot water usage has not changed, a hot water supply line slab leak may be drawing hot water continuously from the tank.

How Polly Plumbing Detects a Slab Leak

Slab leak detection is not guesswork and it is not drilling holes in the floor until you find something wet. Brent uses a combination of three non-invasive methods to locate the exact leak point before any repair work begins.

Pressure testing and isolation. Brent first confirms there is a supply line leak by isolating the hot and cold systems separately and pressure testing each. This confirms whether the leak is in the hot supply side, the cold supply side, or a drain line — which shapes the detection approach and the repair options.

Electronic leak detection with listening equipment. Acoustic leak detection amplifies the sound of water escaping under pressure through the slab. An experienced operator can localize the leak to within 12 to 18 inches of the actual failure point by moving the listening sensor across the floor surface. Brent uses this method to identify the general zone of the leak without any floor penetration.

Thermal imaging for hot water line leaks. For hot water supply line slab leaks, a thermal imaging camera detects the temperature anomaly on the floor surface above the leak. Hot water escaping under the slab warms the concrete above it, producing a visible heat signature. This method is highly effective for locating hot water slab leaks quickly and accurately.

The combination of pressure testing, acoustic detection, and thermal imaging produces a leak location with enough accuracy to plan the repair approach before opening the floor.

Detection cost: $326 (Polly Plumbing pricebook item E-001).

A Real Call: The Keller Home With Three Months of Confusion

Sandra called from a 1993 Keller home in a neighborhood off Pate Road. Her water bill had been climbing for three months — from roughly $85 per month to $178 per month. Her plumber had checked every fixture, every toilet, every appliance. Nothing was running. The irrigation system was confirmed off.

Brent arrived and ran pressure isolation. Cold supply line pressure held. Hot supply line pressure dropped steadily — a hot water supply line was losing water under pressure somewhere. Thermal imaging revealed a distinct heat zone approximately 14 feet from the water heater in the living room floor, consistent with a hot water supply line failure at a fitting.

Sandra’s home was a 1993 build. Original copper supply lines. Thirty-two years of Blackland Prairie clay movement applied to a copper elbow at a direction change in the supply line run. The fitting had developed a pinhole. At an estimated loss rate of 8 gallons per hour, the three-month cumulative loss was approximately 17,000 gallons — essentially the water bill anomaly she had been seeing.

The detection cost was $326. Brent discussed the three repair options with Sandra that afternoon.

Three Repair Options for Keller Slab Leaks

After detection, the repair method is the most consequential decision. There are three options, each appropriate in different circumstances. Brent presents all three with pricing and an honest recommendation on every slab leak call.

Option 1: Spot Repair Through the Slab

What it is: Opening the concrete slab at the exact leak location, accessing and repairing the failed pipe section, and repatching the concrete.

Cost: $5,053 (Polly Plumbing pricebook item SLB-002).

When it is the right choice: The leak is isolated to a single point. The rest of the under-slab copper system is in good condition (confirmed by inspection). The home has had no previous slab leaks. The leak is in a location where floor material removal and concrete cutting is manageable.

When it is not the right choice: The home has had previous slab leaks. Pressure testing reveals multiple weak points in the supply system. The copper pipe system is 30 or more years old throughout and showing systemic corrosion. A spot repair on a pipe system with multiple failure points is a temporary fix.

Option 2: Re-Route Overhead

What it is: Abandoning the failed under-slab supply line entirely and running a new supply line through the walls and ceiling above the slab to bypass the failure. The new pipe never touches the concrete or the clay soil.

Cost: $4,176 (Polly Plumbing pricebook item SLB-006).

When it is the right choice: The home has had previous slab leaks. The copper system is 30 or more years old with systemic corrosion risk. The homeowner wants to eliminate future slab leak risk on the affected supply line permanently. The overhead re-route is frequently the more cost-effective long-term choice on older Keller homes with original copper — it costs less than a spot repair and eliminates the slab leak risk on the re-routed line permanently.

When it is not the right choice: The architectural layout of the home makes an overhead re-route extremely difficult without significant wall and ceiling access. In those cases the spot repair or tunnel option is more practical.

Option 3: Tunnel Access

What it is: Tunneling beneath the slab from the exterior of the home to access the failed pipe without cutting through the interior floor. The tunnel provides access to repair the pipe, then the tunnel is backfilled.

Cost: $5,035 for up to 5 feet of tunnel (Polly Plumbing pricebook item EX-004).

When it is the right choice: The failed pipe is located in a finished area where floor disruption would damage valuable flooring (hardwood, custom tile) and the overhead re-route is not architecturally feasible. The tunnel avoids all interior floor disturbance.

When it is not the right choice: The leak is far from the exterior wall, making the tunnel length prohibitive. Cost increases with tunnel length beyond 5 feet.

What to Do While Waiting for Detection

If you suspect a slab leak, these steps limit damage while you wait for Brent:

Reduce hot water use if the suspected leak is on the hot side. If you are hearing running water only when the hot water is being used, or if you have a warm floor spot, reducing hot water consumption reduces the ongoing loss rate while you wait for detection.

Do not ignore it waiting for it to get worse. A slab leak that saturates the clay beneath the foundation for weeks or months does progressive damage that accelerates the longer it runs. The detection call is $326. The structural damage from a leak that saturates the subfloor and promotes mold growth can cost significantly more.

Document any floor, wall, or foundation changes. Photograph any new floor staining, wall cracks, or flooring warping. This documentation is useful for homeowner’s insurance claims if the leak has produced structural damage.

Slab Leak Detection and Repair Costs in Keller TX

All pricing includes labor and materials as specified. Written quote before any work begins. For slab leaks producing active water damage, same-day detection is available Monday through Friday 8am to 4pm and Saturday 8am to 2pm. Live agents answer 24/7 to book.

What Polly Plumbing Does on Every Keller Slab Leak Call

When you call Polly Plumbing for slab leak detection in Keller or anywhere in Tarrant County, the live agent books the appointment and asks for your address and what symptoms you have observed. Brent arrives with pressure testing equipment, acoustic detection gear, and a thermal imaging camera.

He performs pressure isolation to confirm which supply side is leaking. Then he uses acoustic detection and thermal imaging to localize the leak point. Finally he documents the leak location on a floor plan sketch. He then presents all three repair options with pricing — spot repair through slab, re-route overhead, and tunnel access — and makes a specific recommendation based on the leak location, the pipe system age, and the home’s repair history.

You receive everything in writing before any work begins.

For general electronic leak detection and hidden wall leak services, see our leak detection guide for Keller TX.

Service areas for slab leak detection: Southlake, Colleyville, Flower Mound, North Richland Hills, Grapevine, Fort Worth, Arlington, Trophy Club, Roanoke, and all of Tarrant County.

Call (817) 286-3446 any time. Live agents answer 24/7. No emergency surcharge.

Frequently Asked Questions About Slab Leak Detection in Keller TX

How much does slab leak detection cost in Keller TX?

Polly Plumbing’s slab leak detection fee is $326. This covers pressure isolation testing to identify which supply side is leaking, acoustic listening equipment to localize the leak point, and thermal imaging for hot water line leaks. A written leak location report and repair recommendations are included. The $89 dispatch fee is waived for PollyCare members. Call (817) 286-3446.

What are the signs of a slab leak in a Keller TX home?

The most common signs are an unexplained increase in the water bill, the sound of running water when all fixtures are off, a warm or damp spot on the floor, foundation cracks or doors and windows that have started sticking, and a mold or mildew odor without a visible source. In Keller, slab leaks are most common in pre-1995 homes with original copper supply lines due to 30-plus years of Blackland Prairie clay movement. Call Polly Plumbing at (817) 286-3446.

Why are slab leaks so common in Keller TX?

Two compounding factors. Tarrant County’s Blackland Prairie clay soil documented by the USGS has very high shrink-swell potential — it expands significantly when wet and contracts sharply when dry. This seasonal movement applies repeated bending stress to the copper supply lines embedded beneath the slab. Combine that soil movement with copper pipe that is 25 to 40 years old and you get the predictable result: stress fracture failures at fittings, elbows, and direction changes in the supply line run.

What are my repair options for a Keller TX slab leak?

Three options. Spot repair through the slab: cutting the concrete at the leak location, repairing the pipe, and repatching. Cost: $5,053. Best for isolated leaks on newer pipe systems. Re-route overhead: abandoning the failed under-slab line and running new pipe through the walls above the slab. Cost: $4,176. Best for older pipe systems with systemic corrosion risk or repeat slab leaks. Tunnel access: tunneling beneath the slab from the exterior to access the pipe without cutting interior flooring. Cost: $5,035 for up to 5 feet. Best when floor disruption is not acceptable. Brent recommends the appropriate option in writing after detection.

Is the overhead re-route cheaper than cutting through the slab?

Yes. Polly Plumbing’s re-route overhead is $4,176 versus $5,053 for spot repair through the slab. For older Keller homes with original pre-1995 copper and a history of slab leak concerns, the re-route is often both cheaper and more effective long-term because it eliminates the under-slab vulnerability on the re-routed line permanently. Brent presents both options with pricing on every slab leak call so you can make an informed choice.

How long does slab leak detection take in Keller TX?

A typical detection visit takes 1.5 to 2 hours from arrival to written report. Pressure isolation testing takes approximately 20 to 30 minutes. Acoustic and thermal detection to localize the leak point takes another 30 to 60 minutes depending on the floor plan. Brent documents the leak location on a sketch and presents repair options with pricing before leaving. Call Polly Plumbing at (817) 286-3446 for same-day detection.

Can a slab leak damage my foundation in Keller TX?

Yes, and in Keller specifically the foundation damage risk is higher than in most markets because of the Blackland Prairie clay. A slab leak that saturates the clay beneath the foundation causes the clay to swell unevenly, which can push sections of the foundation upward. When the leak is repaired and the clay dries, uneven settlement can occur. A slab leak that runs for months before detection can produce foundation movement that results in visible cracks, door and window alignment problems, and structural damage costing significantly more than the plumbing repair itself. Early detection is the critical protective step.

Written by Brent Applegate, Licensed Master Plumber, Polly Plumbing. Texas License RMP-42199. Based in Keller, TX. Serving Keller and all of Tarrant County.

Published: May 2026. Last reviewed: May 2026.