Slab Leak Detection & Repair in McLean, VA
Warm spot on the floor, water seeping through tile or a meter that never stops? We pinpoint leaks under basement and slab floors, then repair or reroute the line.
- Electronic location first
- Spot repair or reroute
- Open 24/7
A slab leak is a leak in a pipe that runs under a concrete floor. In McLean that usually means a basement slab, a slab-on-grade addition, a sunroom, a garage or a townhome. Because the pipe is buried, the leak can run for weeks before anyone sees water. Our job is to find the exact spot first so you are not paying to break up more concrete than needed. If you are not sure you have one, our guide to what a slab leak is covers the signs, and our main leak detection service covers leaks anywhere in the house.
What our slab leak service includes
- Meter and pressure tests to confirm the leak and find which line is losing water.
- Acoustic and thermal location to pinpoint the leak under the slab.
- Moisture mapping around the area to see how far water has spread.
- A side-by-side explanation of spot repair, reroute and repipe options.
- The repair itself, a pressure test afterward and a meter recheck.
- Patching the access opening in the concrete when a spot repair is chosen.
Signs and causes of slab leaks
| Sign | What it can mean |
|---|---|
| Warm or hot spot on the floor | Hot-water line leaking under the slab |
| Water seeping at a floor joint or crack | Supply or drain line leak, or groundwater (we test to tell them apart) |
| Running water sound with fixtures off | Pressurized supply line leak |
| Meter leak indicator spinning | Water leaving the system somewhere |
| Damp carpet, lifting vinyl or cupping wood | Moisture rising through the slab |
| New cracks in floor or walls | Soil movement, sometimes from a long-running leak |
Common causes include corrosion of older copper, abrasion where pipe rubs on concrete or gravel, poor joints made when the home was built, high water pressure and soil movement. Northern Virginia's clay soil swells and shrinks with moisture, which puts stress on rigid pipe.
How slab leak repair works in McLean
- Confirm and isolate. A meter test confirms the leak. Pressure tests on hot and cold lines tell us which one is leaking.
- Pinpoint. Acoustic microphones on the floor listen for escaping water. Thermal imaging shows warm patches from hot-water leaks. We mark the spot.
- Choose the fix. We walk you through the options below, including what each means for your floors and future leaks.
- Repair. For a spot repair we cut a small opening, replace the failed section and pressure test before closing. For a reroute we run new pipe through walls, ceilings or the basement and cap the old line.
- Test and restore. We retest the system and check the meter. Concrete is patched for spot repairs; drywall openings for reroutes are left ready for finishing.
Slab leak repair options compared
| Option | What happens | Good fit when | Trade-off |
|---|---|---|---|
| Spot repair | Open the slab over the leak and replace that section | One leak, sound pipe, easy access | Other old sections may leak later |
| Reroute | New line through walls or ceilings; old line abandoned | Older pipe, repeat leaks, finished floors | Some drywall work |
| Partial or full repipe | Replace a branch or all supply lines | Several leaks, pinholes, old galvanized or polybutylene | Larger project |
In homes with basements, a reroute can often run overhead through the basement ceiling, which avoids breaking up a finished floor.
What affects the cost
- Depth and location of the leak under the slab.
- Floor finish over it: carpet, tile, hardwood or bare concrete.
- Spot repair versus reroute length.
- Pipe material and age.
- Permits required by Fairfax County.
- Water damage cleanup, which is separate from the plumbing repair.
We explain the price for each option after the leak is located.
DIY vs calling a pro
You can check the meter with everything off and feel for warm spots with bare feet. If the meter moves, shut off the main valve when you are away and call. Do not chip at concrete to look for a leak; without location equipment you can damage pipes, radiant heat lines or wiring. A professional location takes the guessing out of a costly repair.
Insurance and permits in Virginia
Virginia's Bureau of Insurance tells homeowners to give immediate notice of a possible claim and to protect the property from further damage. Many policies handle damage from water differently from the pipe repair itself. Our guide to slab leak insurance explains the questions to ask your agent. Fairfax County requires a plumbing permit to replace or repair plumbing equipment; we tell you when your job needs one.
Local note
Basement slabs are the norm in Oakton and Vienna colonials. Townhomes and cluster homes in Reston and Herndon are more likely to be slab-on-grade, so leaks often show through first-floor tile or wood.
Slab leak repair questions
What are the signs of a slab leak?
Common signs are a warm spot on the floor, damp or cracked flooring, the sound of running water with everything off, a water meter that keeps moving, a sudden jump in the water bill and low pressure. In a basement you may see water seeping up at a joint or crack.
Do McLean homes have slab leaks if they have basements?
Yes. A basement floor is a concrete slab, and supply or drain lines can run under it. Additions, sunrooms, garages and many townhomes also sit on slabs.
Should I repair the leak or reroute the pipe?
A spot repair suits one leak in otherwise sound pipe that is easy to reach. A reroute suits older pipe, repeat leaks or a leak under a finished area. We explain both options and their trade-offs before work starts.
How long does slab leak repair take?
A spot repair is often finished in a day, though concrete patching and flooring may need more time. A reroute is usually one or two days, depending on the pipe path and how much wall or ceiling must be opened.
Is slab leak repair covered by insurance?
It depends on the policy. Many policies treat sudden water damage differently from the cost to repair the pipe itself. Read our guide on slab leak insurance and call your agent.
Can a slab leak damage my foundation?
Water under a slab can soften soil and wash it away over time, which can lead to settling and cracks. Fixing the leak early limits how much soil is affected.
Sources
- U.S. EPA WaterSense — Fix a Leak Week
- Fairfax County Land Development Services — Residential Plumbing Permit
- Virginia State Corporation Commission, Bureau of Insurance — Homeowners Insurance Consumer's Guide
Last reviewed 2026-11-07. This page is general information, not legal or insurance advice. Read how we research and check pages in our editorial policy.
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Helpful guides
Leaks & DetectionWhat Is a Slab Leak?
How to tell if a pipe is leaking under your concrete floor, and what fixing it involves.
Costs & InsuranceSlab Leak Insurance
What Virginia homeowners policies often cover after a slab leak, what they exclude and how to file.
Seasonal & EmergenciesWater Through Basement Floor
Tell groundwater from a plumbing leak, and know whether you need a sump pump, a plumber or both.
Warm floor or water coming through concrete? Call for slab leak help.
Call McLean Plumber Works any time, day or night. A plumber picks up and talks you through next steps.