By Brent Applegate, Licensed Master Plumber | Polly Plumbing | License No. RMP-42199 Serving Keller, Southlake, Colleyville, Flower Mound, North Richland Hills, Grapevine, Trophy Club, Roanoke, and all of Tarrant and Denton Counties. Based in Keller, TX.
Slab Leak Detection in Keller TX: Signs, Costs, and the Three Repair Options Explained
Water is pooling somewhere it should not be. Or your water bill jumped $80 last month without explanation. Or there is a warm spot on the kitchen floor that was not there last spring.
These are the calls Polly Plumbing gets from Keller homeowners who have been watching something odd for weeks, hoping it would resolve itself. Slab leaks do not resolve themselves. In Keller, they get worse — and faster than in most North Texas cities — because of what is under your foundation.
Keller sits on Blackland Prairie clay, the same expansive soil formation documented by the U.S. Geological Survey across Tarrant County. This clay expands significantly when wet and contracts in dry conditions. That seasonal cycle — wet spring, dry summer, wet fall — stresses every pipe beneath your slab at every joint and bend, every year. Combined with Keller’s municipal water supply, which the City of Keller’s annual water quality reports confirm is drawn from Tarrant County’s hard water system, the pipes under older Keller homes face both mechanical stress from soil movement and chemical corrosion from mineral-rich water simultaneously.
Of the last 40 slab leak detection calls Polly Plumbing completed in Keller and surrounding Tarrant County cities, 31 involved homes built before 1995 with original copper supply lines. That is not a coincidence. It is the predictable result of aging copper pipe operating in Blackland Prairie clay for 30 or more years.
This guide explains how to recognize a slab leak in a Keller home, how detection works, what it costs, and the honest trade-offs between the three repair methods. Call (817) 286-3446 to schedule a detection visit. Live agents answer 24/7 to book your appointment.
Written by Brent Applegate, Licensed Master Plumber at Polly Plumbing in Keller, TX. Brent holds Texas Master Plumber License RMP-42199 and performs slab leak detection and repair throughout Keller and Tarrant County.
The Call Brent Did Not Expect
Maria called on a Thursday morning. She had noticed a faint smell of mildew in her hallway for about three weeks and assumed it was coming from the HVAC return. A service company had inspected the HVAC and found nothing. She was calling Polly Plumbing as a second opinion.
Her home was a 1988 build in a neighborhood off Keller Parkway. Slab foundation. Original copper supply lines. When Brent arrived, he pressed the carpet near the hallway baseboard. It compressed with a faint wet sound.
The acoustic detection scan found the leak signature 18 inches inside the hallway wall line — a hot water supply line running under the slab to the master bath. Thermal imaging confirmed it: a heat signature spreading outward in the concrete below the hall flooring.
The leak had been running for weeks. The mildew smell was not the HVAC. It was moisture migrating up through the slab, saturating the carpet pad, and beginning to grow mold behind the baseboard.
What surprised Maria was how small the actual pipe failure was. A pinhole. A single corroded point on a 35-year-old copper line. That pinhole had been running silently — no visible water, no dramatic flooding, just a slow migration of moisture through concrete and into her home.
Brent presented three repair options in writing. Maria chose the overhead re-route. The compromised copper line was abandoned and a new supply line was run through the walls above the slab. The mold behind the baseboard was a separate remediation call — plumbing first, then remediation. That sequencing matters.
Why Keller Homes Have More Slab Leaks Than Most North Texas Cities
Three factors converge in Keller specifically.
Blackland Prairie clay beneath the foundation. The USGS geological survey of Tarrant County documents the Blackland Prairie clay formation that underlies much of Keller. This soil has high shrink-swell potential — it expands measurably when saturated and contracts during dry periods. A Keller home’s foundation moves slightly with every significant rain and every dry stretch. Over 30 or 40 years, that cumulative movement fatigues copper pipe at the points of least flexibility: joints, bends, and anywhere the pipe is in contact with the concrete or the shifting soil below it.
Hard water mineral corrosion on copper pipe exteriors. The City of Keller’s water supply comes from Tarrant County’s municipal system — among the hardest water in Texas, with hardness levels that place it in the “very hard” category per EPA classification standards. That mineral-rich water, when it contacts the exterior of copper pipes beneath the slab through soil moisture, accelerates the pitting corrosion that eventually produces the pinhole failures Brent finds on detection calls.
Original copper supply lines in pre-1995 homes. Keller’s established neighborhoods were largely built between the mid-1970s and the early 1990s. Copper supply lines installed during that period are now 30 to 50 years old. The combination of age, Blackland Prairie clay movement, and hard water exterior corrosion makes these lines statistically likely to develop failures — not a matter of if, but when.
The Seven Warning Signs of a Slab Leak in a Keller TX Home
Sign 1: Water Bill Increase With No Explanation
A water bill that jumps 15 to 40 percent without a change in household usage is the most common early signal. The leak runs continuously — 24 hours a day — whether you are home or not. Most Keller homeowners attribute the first billing cycle increase to an anomaly and wait. By the second billing cycle the pattern is undeniable.
Check your meter first. Turn off every fixture in the house and watch the meter dial for 15 minutes. If it moves with nothing running, water is leaving the system somewhere.
Sign 2: Warm or Wet Spot on the First Floor
A hot water line leak heats the concrete above it. That warmth transfers through tile, hardwood, or carpet as a spot that is noticeably warmer than the surrounding floor. Remove your shoes and walk the first floor. Any spot that is distinctly warmer than its surroundings on a day when the floor is otherwise uniform temperature is worth noting.
Wet or soft spots in flooring — carpet that feels damp, tile that sounds hollow, hardwood that is slightly raised — with no visible water source above are slab leak signals until proven otherwise.
Sign 3: Sound of Running Water With Everything Off
On a quiet evening with every fixture, appliance, and irrigation off, press your ear to the floor in the kitchen, bathrooms, and main hallway. A faint hissing or rushing sound is the acoustic signature of pressurized water escaping a pipe beneath the slab. This sound is audible through concrete at close range in a quiet house.
If you hear it, call Polly Plumbing the same day.
Sign 4: Low Water Pressure at Multiple Fixtures
A supply line slab leak diverts volume away from your fixtures. If your shower pressure has dropped and multiple fixtures throughout the house feel weak simultaneously — and the city supply pressure tests correctly at the meter — the loss is happening inside the system. A supply line slab leak is one of the most common causes of whole-house pressure reduction in Keller homes.
Sign 5: Mold or Mildew Smell Without a Visible Source
Maria’s story above is the pattern. A persistent mold smell on the first floor, particularly in rooms without plumbing above, is often moisture migrating up through the slab from a leak below. The concrete wicks the water upward. It saturates the subfloor and begins growing mold under the flooring or behind baseboards before any visible moisture appears above the surface.
If you smell mold and cannot find the source after checking every room and the HVAC system, a slab leak detection visit is the next step.
Sign 6: Cracks in Flooring or Baseboards
When a slab leak saturates the Blackland Prairie clay beneath the foundation, that clay expands. The expansion can lift sections of the slab unevenly. The visible result is cracked tile grout, gaps in hardwood flooring, or cracked or separated baseboard trim along the wall at floor level.
This sign means the leak has been running long enough to affect the foundation. Plumbing repair is urgent. Foundation evaluation after the water source is eliminated is also warranted.
Sign 7: Foundation Settlement or Door and Window Issues
The most severe consequence of an unaddressed slab leak in Keller’s expansive clay is uneven foundation settlement — the soil softens, the foundation moves, and doors begin sticking, windows develop gaps, and diagonal cracks appear in drywall running from door and window corners.
At this stage the plumbing problem has become a structural problem. The leak must be stopped before any foundation evaluation or remediation is meaningful.
How Slab Leak Detection Works in Keller TX
Detection is not guesswork. Breaking concrete without a precise leak location produces unnecessary floor damage and frequently misses the pipe. Professional non-destructive detection locates the leak to within a few inches before any tool touches the floor.
Polly Plumbing uses three detection methods in combination on every Keller slab leak call.
Acoustic listening equipment amplifies the sound of pressurized water escaping a pipe beneath the slab. Readings are taken at multiple points across the floor surface. An experienced plumber interprets the acoustic data to triangulate the location. Acoustic detection is the primary tool for pressurized supply line failures — the most common slab leak type in Keller.
Thermal imaging reads floor surface temperatures across the search area. A hot water line leak creates a heat signature visible through the thermal camera. Thermal imaging confirms what the acoustic data suggests and provides a second data point for precise location.
Pressure isolation testing shuts down hot and cold supply lines independently while monitoring pressure drop at the meter. This confirms which line is leaking — hot or cold — and gives a rough indication of the leak’s severity before any floor is opened.
The three methods together produce a marked location on the floor and a written summary of findings. All three repair options with pricing are presented before any work begins.
Detection fee: $426. Applied toward the repair cost when Polly Plumbing performs the repair.
The Three Repair Methods: Costs and Honest Trade-Offs for Keller Homeowners
Method 1: Repair Through the Slab
Cost: competitive band $3,790 to $6,320
Polly Plumbing breaks through the concrete at the detected location, excavates to the pipe, repairs or replaces the failed section, patches the concrete, and tests the repair. Interior finish flooring damaged to access the slab — tile, hardwood, carpet — is the homeowner’s responsibility.
When it is the right choice: The pipe is relatively new, the failure is clearly isolated, and the rest of the line is in good condition. If the copper beneath the slab still has meaningful service life remaining, a targeted repair at the single failed point makes economic sense.
The honest trade-off: You are fixing one section of the original pipe while leaving the rest in place. For a 1988 Keller home with original copper in Blackland Prairie clay, the pipe that failed is operating in the same conditions as every other section of the same pipe. A second failure in a different location within a few years is a real possibility. Lowest upfront cost, but not necessarily the lowest cost over a five-year horizon.
Method 2: Overhead Re-Route
Cost: competitive band $3,130 to $5,220
Polly Plumbing cuts off the compromised slab line at both ends, abandons it in the slab, and runs a new supply line through the walls and ceiling to bypass the slab entirely. The new line runs through conditioned, accessible space rather than buried in concrete and clay. Wall opening where the new line enters and exits is the homeowner’s responsibility unless quoted separately.
When it is the right choice: The home is pre-1995 with original copper, this is the first detected slab leak on the line, or the leak location makes through-slab access particularly destructive. The re-route eliminates the original compromised line from the system entirely.
Brent’s recommendation for most Keller pre-1995 homes: This is the conversation worth having before defaulting to through-slab repair. A 35-year-old copper line in Blackland Prairie clay that has produced one failure is statistically more likely to produce a second failure than a line that has not yet failed. The overhead re-route costs slightly less than through-slab repair, eliminates the aging line from the system, and puts the new supply pipe in a location where the next plumber can actually see it.
The honest trade-off: More wall disruption during installation than through-slab repair. Some homeowners prefer the minimal interior impact of a targeted slab repair even knowing the rest of the line remains in place.
Method 3: Tunnel Access
Cost: competitive band $3,780 to $9,290
Polly Plumbing tunnels under the foundation from outside the home to reach the leak location without breaking interior flooring. The repair is made through the tunnel. This method preserves the interior floor finish.
When it is the right choice: High-value interior finish flooring — custom tile, premium hardwood, natural stone — where flooring replacement would be as expensive as the plumbing repair itself. Brent assesses tunnel feasibility at the detection visit based on the foundation geometry and exterior grade.
The honest trade-off: More labor-intensive and adds project time. Not feasible in every location depending on the foundation layout and how close the leak is to the exterior wall.
What a Slab Leak Costs If You Wait
Keller’s Blackland Prairie clay makes delay more expensive than in most markets. The saturated soil does not just sit there — it expands, migrates, and softens the load-bearing layer beneath the foundation. Here is the realistic cost escalation of an unaddressed slab leak in Keller.
Month 1 to 2: Water bill increase of $50 to $150 per month. Moisture beginning to migrate upward through the slab. Subfloor materials beginning to absorb moisture.
Month 2 to 4: Mold developing under flooring and behind baseboards. Flooring adhesive failing in affected areas. Water bill increase becomes significant. Subfloor damage begins requiring remediation beyond plumbing repair.
Month 4 to 8: In Keller’s expansive clay, sufficient soil saturation can begin affecting foundation load distribution. Hairline cracks in tile and grout. Possible early drywall cracking.
Beyond 8 months: Foundation evaluation required in addition to plumbing repair. Combined plumbing, mold remediation, flooring replacement, and foundation assessment can reach $20,000 to $40,000 — multiples of the $4,000 to $5,000 plumbing repair that would have addressed the issue at month one.
The detection visit at $326 is the investment that determines which scenario you are in.
What Polly Plumbing Does on Every Keller Leak Detection Call
When you call Polly Plumbing for a leak detection service in Keller TX, Brent asks a few questions before arriving. How long the symptoms have been present, which area of the home is affected, whether the water bill has increased, and whether the home is pre-1995 construction. You get a text with his photo before he knocks.
The detection visit covers acoustic listening at multiple points across the first floor, thermal imaging of the search area, pressure isolation testing to confirm the affected line, and a written summary with the marked location. If the detection is inconclusive — which can occur with very small or slow leaks — Brent returns to re-locate at no additional charge.
Every repair option is presented in writing with a price for each before any work begins. Brent makes a recommendation and explains the reasoning. The decision is always yours.
For same-day leak detection service in Keller, live agents answer 24/7 at (817) 286-3446. No emergency surcharge.
Other Tarrant and Denton County service areas for leak detection and slab leak repair: Southlake, Colleyville, Flower Mound, North Richland Hills, Grapevine, Trophy Club, Roanoke, and all of Tarrant County and Denton County.
Frequently Asked Questions About Slab Leak Detection in Keller TX
How do I know if I have a slab leak in my Keller TX home?
The most common early signs are an unexplained water bill increase, a warm or wet spot on the first floor, and the sound of running water when all fixtures are off. Keller homes built before 1995 with original copper supply lines are at elevated risk because of the combination of pipe age and seasonal movement in Blackland Prairie clay. Of the last 40 slab leak detection calls Polly Plumbing completed in Keller and Tarrant County, 31 involved pre-1995 homes with original copper lines. If you notice any of these signs, call (817) 286-3446 before the damage escalates.
How much does slab leak detection cost in Keller TX?
Polly Plumbing’s leak detection and location service is $326, applied toward the repair cost when Polly performs the repair. The visit covers acoustic listening equipment, thermal imaging, pressure isolation testing, a written summary, and the marked leak location. If the detection is inconclusive on the first visit, Brent returns to re-locate at no additional charge. Call (817) 286-3446 to schedule.
What are the repair options for a slab leak in Keller TX?
Three methods are available. Repair through the slab breaks concrete at the leak location and costs approximately $5,053 — the right choice for newer pipe with an isolated failure. An overhead re-route abandons the compromised slab line and runs new pipe through the walls at approximately $4,176 — often the better long-term choice for pre-1995 Keller homes with original copper. Tunneling under the foundation preserves interior flooring at approximately $5,035 for up to 5 feet — the right choice when finish flooring replacement would rival the plumbing repair cost. All three options are presented in writing before any work begins.
Why are slab leaks common in Keller TX?
Keller sits on Blackland Prairie clay documented by the USGS as having high shrink-swell potential. That soil expands and contracts with every rain cycle and dry period, stressing underground pipes at joints and bends every year. Combined with original copper supply lines in pre-1995 homes and hard water mineral corrosion, the combination of mechanical stress and chemical attack produces pipe failures that are more common in Keller than in newer markets with different soil profiles.
Is the overhead re-route better than breaking through the slab for a Keller home?
For most pre-1995 Keller homes with original copper supply lines, yes. A 35-year-old copper line in Blackland Prairie clay that has produced one failure is operating under the same conditions as every other section of the same pipe. Repairing one point leaves the rest of the aging line in place. The overhead re-route eliminates the compromised line from the system entirely and costs approximately $4,176 — slightly less than through-slab repair. Brent presents both options with pricing and explains the trade-offs in writing on every detection call.
How long can I wait to fix a slab leak in Keller TX?
Do not wait. In Keller’s expansive Blackland Prairie clay, a slab leak that saturates the soil beneath the foundation begins affecting foundation load distribution within months. What costs $4,000 to $5,000 to repair in the first month or two can become a $20,000 to $40,000 combined plumbing, mold remediation, flooring, and foundation repair project if left unaddressed for six months or more. Call Polly Plumbing at (817) 286-3446 as soon as you notice any of the seven warning signs described in this article.
What is the difference between the Keller leak detection service page and this article?
The Polly Plumbing leak detection service page covers the full range of leak detection services available in Keller including non-slab leaks, pipe leak repair, and whole-home leak assessment. This article focuses specifically on slab leaks — the most common and costly leak type in Keller’s pre-1995 housing stock — with detailed guidance on the detection process, the three repair methods, and the cost escalation of delayed action in Keller’s clay soil environment.
Written by Brent Applegate, Licensed Master Plumber, Polly Plumbing. Texas License RMP-42199. Based in Keller, TX. Serving Tarrant and Denton Counties.
Published: May 2026. Last reviewed: May 2026.