Slab Leak Repair and Detection in Clarksburg, MDLeak located, floor protected.
A slab leak is a water line failure under your concrete floor. We locate it, give you an upfront quote, and repair it without tearing out rooms we do not have to touch. Most homeowners assume a slab leak means a jackhammered living room. Usually it does not.
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What a slab leak is, and whether your home has one
A slab leak is a leak in a pressurized water line that runs beneath a concrete floor slab. The pipe is usually copper, galvanized steel, or polybutylene. The leak is usually small at first, and it hides because concrete holds water out of sight.
Most Maryland homes have basements, so homeowners here often decide slab leaks are a Texas or Florida problem. That is not right. Water lines run under concrete in plenty of Montgomery County homes.
You can have a slab leak if any of the following describes your house:
A slab-on-grade home with no basement, common in newer Clarksburg and Germantown developments
A basement home where supply lines were run under the basement floor slab rather than overhead
A slab-on-grade addition, sunroom, or family room poured off a house that otherwise has a basement
A garage or utility room slab with a water line crossing under it
A townhome or condo where the lowest level sits on poured concrete
A leak outside your foundation footprint is a service line problem, not a slab leak. That is the yard run between the meter and the house. We cover that on our water line repair and replacement page. Our crew tells the two apart before anyone picks up a tool.
One more distinction saves people money. A slab leak is a pressurized supply line, so it shows up as a spinning meter and a rising bill. A drain or sewer line under the same slab fails differently, with backups, gurgling, and slow fixtures. Those get a sewer camera inspection first, then sewer line repair or replacement if the line is compromised.
Signs of a slab leak in a Montgomery County home
The early signs are quiet and easy to explain away. The later ones are expensive.
Catch it early
- Your water bill jumped with no change in how you use water
- You hear running water when every fixture in the house is off
- Water pressure dropped across the whole home, not at one faucet
- The dial on your water meter keeps creeping with everything shut off
Catch it late
- A warm or hot spot on the floor, pointing to a hot water line under the slab
- Damp carpet, buckled flooring, or a dark line along the baseboard
- A musty smell, mildew, or mold along an interior wall
- New cracks in the floor slab or in the foundation
- Standing moisture in a finished basement with no roof or window source
The five-minute meter test
Turn off every fixture and appliance that uses water. Find your water meter and note the reading or the position of the low-flow dial. Wait 30 minutes without using water. Read it again. Movement means water is escaping somewhere in your system. That test tells you a leak exists, not where it is. Finding where is our job.
Copper pinhole leaks and WSSC water
In Montgomery County, most slab leaks we open up are copper pinhole leaks. Copper corrodes from the inside, a pinhole opens, and pressure does the rest.
This is a documented regional problem, not a theory. WSSC Water has investigated copper pipe pinhole leaks since 1999, and began adding orthophosphate, a corrosion inhibitor, in late 2003. WSSC also states plainly that it is not responsible for home and commercial plumbing systems. The pipe inside your foundation is yours.
Copper installed before that treatment change has had decades of exposure. We see it most in homes built between 1970 and 2000, across Gaithersburg, Rockville, and Germantown. Corrosion is not the only cause. We also find:
- Soil movement and settling that puts a bend or stress point on a rigid line
- Hot water lines abrading against concrete or rebar as they expand and contract
- High static pressure accelerating wear on aging copper
- Installation shortcuts, including unprotected pipe laid directly against the slab
The cause matters because it changes the repair. One pinhole from an isolated stress point is a spot repair. One pinhole in 40-year-old copper is usually the first of several.
Slab leak detection without tearing up your floor
Finding a slab leak is different from finding a leak you can reach. The pipe is encased in concrete, so we work by elimination before anyone touches the floor.
We isolate the hot and cold sides separately and watch which one loses pressure. A warm spot on the floor almost always means the hot line failed. Then we listen through the slab with sonic equipment and trace the actual pipe route, which is rarely where the plans put it. By the time we mark the floor, we are marking a spot measured in inches, not a room.
Our team owns this equipment and runs it in house. It is the same leak detection setup we bring to hidden pipe leaks, pool lines, and buried service lines.
One honest note, because it saves people money
A paid leak detection is not always necessary. We have seen enough of these to scope and quote many slab leaks without billing a full detection first. When the cost of detecting exceeds the benefit, we say so. On a long run, a commercial slab, or a shared line, guessing means digging the wrong 40 feet, and there detection pays for itself immediately.
Slab leak repair options, and how we pick yours
There are four ways to fix a slab leak. We recommend one, explain why, and leave the decision with you.
Spot Repair
We open a small section of concrete over the leak, cut out the failed piece, and splice in new pipe. Fastest and cheapest, right when the pipe is otherwise sound and it is the first failure on that line.
Reroute the Line
We abandon the pipe under the slab and run a new line overhead or through walls. Nothing gets jackhammered. Best under a finished floor, a kitchen island, or tile worth saving.
Repipe the Affected Run
One section fails and the rest of that run is the same age and condition. Replacing the whole run beats chasing pinholes. You pay once instead of three times.
Whole-Home Repiping
If pinholes show in more than one place, the copper itself is the problem. We repipe in PEX or copper, handle permits and inspections, and use bypass valves so your family stays home. A typical 3 bed / 2 bath runs about three days.
The decision rule we use is simple. One leak in newer pipe gets a spot repair. Repeat leaks in aging copper get replaced, because a fourth spot repair costs more than the repipe you were avoiding.
If the failure turns out to be in the line outside, the same repair-or-replace math applies underground. Our guide to trenchless versus traditional sewer repair walks through that decision in Montgomery County terms.
How your slab leak repair goes, step by step
A straightforward spot repair is often a same-day job. A reroute or partial repipe typically runs one to three days.
We confirm the leak and locate it
Acoustic, thermal, and pressure testing narrow it to a spot and a depth. We open only what we must.
We give you an upfront quote
Repair versus reroute versus replacement, flat pricing, before any work starts.
We protect the space
Floor coverings, containment, and dust control go in before the first cut.
We make the repair
Spot repair, reroute, or replacement, using the method you approved.
We test before we close
Pressure test the line and verify the leak is gone.
We restore the area
We patch concrete and put the space back as close to how we found it as possible. Finish flooring and drywall goes to referral partners when it falls outside plumbing scope.
Slab leak repair cost in Maryland, and what changes the price
There is no single price, so here is how the number gets built.
Leak detection, when a job genuinely needs it, runs from $650 to $2,150. The low end is a standard residential daytime detection. The high end reflects nighttime, weekend, emergency, and commercial work, like isolating a line under a parking lot or a large building.
Sometimes the leak is in your outside water or sewer service line instead. There, trenchless sewer and water line replacement can often skip the trench entirely. Underground repairs in this area run from $1,500 to more than $20,000. Depth past 10 feet, rocky ground, sidewalks, driveways, street proximity, and permit and inspection requirements all push that number up.
Every job gets an upfront quote with flat pricing before work begins. We offer financing through GreenSky when a slab leak lands as a sudden emergency.
Why homeowners choose us after another plumber missed it
We like being the second plumber on the job. Our owner puts it plainly: we find issues other plumbers cannot locate.
Slab leak work is one piece of our underground plumbing division, and that depth is the difference. We have three master plumbers on staff and run our own detection, camera, locating, and trenchless equipment rather than subbing it out. We pull permits before we dig, carry current Miss Utility and OSHA training, and hold WSSC WERI access for main, tap, and connection records.
Our warranties are stated, not implied: repairs carry 90 days, replacements one year, underground excavation three years, and the underground water line pipe carries a lifetime warranty that transfers with the home. When you call at 11 p.m., a member of our own office team answers, not an answering service or a bot. Family owned, women owned, fourth generation, in Montgomery County since 2008. New school plumber, old school values.
Trusted by your neighbors
Rating
We had our first experience with Clarksburg Plumbing & now we're sold! Charlie replaced our powder room toilet & did a great job. We moved to our house 3 years ago (& needed a new plumber) so we're happy to a great plumber now. Highly recommend!
Booked an apt with Clarksburg plumbing at 7am and by 9am they were at my house. Seth was a great tech that explained anything he was doing and answered my questions. would use Clarksburg plumbing again.
Highly recommend John Brown from Clarksburg Plumbing LLC! Yesterday John flushed and descaled our tankless water heater. We've gotten used to waiting and waiting for service people. That's not the case with John. He arrived pleasantly early for both the initial visit (for a no-cost estimate) and for the actual service call. He was personable, knowledgeable, and very patient with our many questions. He really helped us understand the ins and outs of this new-to-us technology of tankless water heaters. We're already recommending him to our neighbors!
John and Maddie were professional and customer focused. They completed several plumbing projects efficiently and verified my satisfaction with the work. John diagnosed a plumbing problem for future remediation. Great people and company.
I had Clarksburg Plumbing come out for a minor home plumbing repair. Seth and Maddie were on time, friendly, and professional. They provided a free estimate, and I went ahead with the repair. The repairs took just under 2 hours and I was completely satisfied with the service. I will definitely use Clarksburg Plumbing again in the future. Thanks, Seth and Maddie!
We had a very good experience with Clarksburg this year. A new fresh water pipe from the street and cleaning the waste pipe. From Brady in the office to John Brown and his team on site (Franklin and Chris) everything went smoothly, successfully, and on time. Would highly recomnend!
Charlie S. was efficient and friendly. He also answered some of my plumbing questions which I greatly appreciate. I will be using Clarksburg Plumbing in the future.
I recently used Clarksburg Plumbing for a condo repair of my main water turnoff valve and my outside hose bib. It required coordination with DC Water and the condo, and Clarksburg was extremely helpful, professional, and patient in the process. They came out a few times to evaluate and troubleshoot the issues, and then ultimately performed/made the repairs. Garrett and John Brown were the first to help, both very kind, knowledgable and highly skilled, and then Pablo (along with apprentice Tevon) made the final repairs. Not only did they do a great job, explaining everything to me in the process and checking after the water was restored to the condo, they also helped out one of the other owners that was having a sudden, luckily minor issue, as well. It’s a relief to know that I finally have a plumbing company that I can rely on for any future issues.
John Brown & Maddie did a great job with installing our new sump pump and battery backup--very informative, patient and thorough.
Many thanks to John and Maddie for their excellent work and cheerful attitude.
We had a fire at our house 3-Jul-2025. Our contractor used Clarksburg Plumbing for all of our plumbing needs as we rebuilt our house. Pablo was with us from the beginning until all work on the house was completed a year later. Pablo was the lead plumber from Clarksburg Plumbing. He worked on the plumbing rough-in in December through February this past winter in bitter cold through the end of July 2026 when work was finally completed. Pablo quietly does his work. It’s clear that he is very skilled but he is not arrogant in any way. Rather, he is very engaging, takes suggestions under consideration and employs them as warranted, and is always kind even when I interrupt his work. Pablo represents Clarksburg Plumbing very well. It was my pleasure working with Pablo.
John & Maddie were great to get me scheduled for a potable water replacement
Properly identified the source of my leak after multiple other plumbers/companies couldn’t figure it out. Were thorough in explaining what they were doing, how they arrived to their determination, and gave advice on how to proceed with next steps that were outside their scope of operations. Thanks Pablo and Tevon
So grateful for you all, after 10 years and multiple plumbers your techs Garrett and Brady found the problem in 10 mins. Professional, friendly, knowledgeable, and we are more than satisfied with the work. Great company, great employees. We have a plumber now!
We had a severe blockage in our kitchen sink drain, causing water to back up into both the sink and the dishwasher. Seth and Brady arrived on time, quickly identified the issue, and did an excellent job clearing the kitchen drain. They also fixed the dishwasher drain line, which is now working perfectly. They were professional, efficient, and courteous throughout the process. I highly recommend them to anyone needing plumbing services.
Recently had an issue with my hot water heater in the restaurant I worked at. Clarksburg plumbing was quick and efficient and I was lucky enough to get John and Maddie as my techs! They were knowledgeable and helpful and fixed the issue in no time. I can’t recommend Clarksburg Plumbing enough and especially John and Maddie. They were honestly wonderful.
John and his assistant, Maddie, replaced an outside water valve and reviewed plumbing in a bathroom. They did excellent work, gave good advice and were friendly and nice. We were pleased with the work and will contact them at Clarksburg Plumbing for any plumbing needs in the future.
John was very knowledgable and provided all the details I needed to make my decision on what I wanted. Matty give me the exact estimates to consider. They were very curteous and professional. Thank you.
John and Maddie arrived on time and were professional and kind! All issues were resolved without issue! Highly recommend!
Happy we called them. It is refreshing to deal with a company a company with great customer service and honest techs. Highly recommend you call them.
Seth was very professional, quick and efficient. Also kind and personable.
Franklin, Chris and Colton, are hard working knowledgeable. They are polite and friendly. They ran into some issues replacing my out side water line. The problems were solved. They cleaned up all debris. I would request this crew if I ever have another plumbing issue. Thank you guys!
Highly recommend Clarksburg Plumbing! They accommodated my schedule right away. John and Maddie were amazing!! They took care of my pipe repair quickly and efficiently! 10/10 recommend!
John and Maddie were the ultimate professionals. Came on time. Clear estimate. Excellent work fixing my pressure relief valve, which had been improperly installed by another plumber. Clarksburg are my go to plumbers from now on.
Where we repair slab leaks
Clarksburg Plumbing repairs slab leaks throughout Montgomery County and Frederick County, Maryland. We work in Clarksburg, Germantown, Gaithersburg, Rockville, North Bethesda, Potomac, Damascus, Boyds, Olney, Poolesville, and the Frederick County towns nearby. See the full service area list.
Slab leak repair FAQ
What is a slab leak?
A slab leak is a leak in a water line beneath your concrete foundation or floor slab. Copper supply lines are the most common culprit in Maryland homes.
How do I know if I have a slab leak?
The clearest early signals are a water bill jump and running water you cannot place, plus whole-home pressure drops and the meter moving with everything off. Warm floor spots, damp flooring, and musty odors mean it has been leaking a while.
Can I have a slab leak if my house has a basement?
Yes. Supply lines are sometimes run under a basement floor slab, and slab-on-grade additions off basement homes are common in Montgomery County. We identify the foundation type and pipe routing before we quote the work.
How much does slab leak repair cost?
It depends on the repair method and access. Leak detection, when needed, runs $650 to $2,150. You get an upfront quote with flat pricing before we start, and we offer GreenSky financing.
Does homeowners insurance cover slab leak repair?
Sometimes, and the distinction matters. Most policies treat sudden, accidental water damage differently from long-term seepage: insurers often pay to access the pipe and for the resulting water damage, but often decline the failed pipe itself as wear and tear. Policies differ, so read yours. WSSC does not cover plumbing inside your property line, and we do not work directly with carriers, but we document the job in full and answer their questions after the work so you can seek reimbursement.
Do you have to break up my whole floor?
No. Most slab leaks are fixed with a small targeted opening or by rerouting the line entirely, with no concrete removed. We tell you which applies before work starts.
How long does slab leak repair take?
A spot repair is often same day. A reroute or partial repipe typically takes one to three days. A full home repipe on a 3 bed, 2 bath house runs about three days.
If I have one pinhole leak, will I get more?
In aging copper, usually yes. Pinholes come from corrosion across the whole system, not one unlucky spot. That is why we recommend replacing a run once it produces repeat leaks.
How long can a slab leak go undetected?
Months, and sometimes years. Concrete hides the water, and the first thing most people notice is the bill. That is why the meter test is worth running the moment you suspect anything.
Does WSSC pay for a pinhole leak in my house?
No. WSSC Water states it is not responsible for home and commercial plumbing systems. It supplies the water; you own the pipe inside your property.
Is a slab leak an emergency?
Treat it as one. Pressurized water under concrete undermines soil, wrecks flooring and framing, and feeds mold. We answer emergency plumbing calls 24 hours a day.
Do you do commercial slab leak detection?
Yes. Frozen and broken lines under parking lots, roadways, shopping centers, and apartment complexes are regular winter work for us. Detection there saves far more than it costs.
Let's Flow.Let's Flow.
You do not need to know whether it is a slab leak, a service line, or something else. Tell us what you are seeing. We will locate it, quote it upfront, and fix it with the least disruption possible. Clarksburg Plumbing LLC, 15300 Croghan Lane, Clarksburg, MD 20871. Available 24/7.
Let's get started
(301) 972 2223
Available 24/7 for Clarksburg and beyond