Slab leaks and foundations
Water lines under a slab can soak the soil beneath it. How to spot a leak, what fixing it costs, and how it ties into foundation work.
Most houses in the Arlington area sit on a concrete slab with water and drain lines running underneath it. When one of those lines leaks, the water goes straight into the soil under the foundation. That's why foundation contractors and engineers so often ask about plumbing first.
Signs of a slab leak
Fixr's slab leak guide lists these warning signs:
- New cracks in the foundation
- A musty smell, or mold
- A water bill that jumps without explanation
- Lower water pressure
- The sound of running water when nothing is on
- Puddles or soggy spots in the yard
What finding and fixing one costs
Fixr's figures, last updated May 1, 2025: leak detection runs $100 to $400, and the average slab leak repair is $2,500, with most between $1,000 and $4,000.
| Repair approach | Fixr range |
|---|---|
| Repairing the broken pipe | $200 to $2,000 |
| Patch | $250 to $800 |
| Pipe lining | $500 to $2,000 |
| Breaking through the slab | $500 to $3,000 |
| Tunneling under the slab | $900 to $2,000 |
| Rerouting the line | $4,000 to $15,000 |
Plumbing and foundation repair go together
- Before lifting: the Texas Section ASCE guidelines call for plumbing tests when a foundation is lifted or jacked. Ask whether tests are done before and after.
- Permits: Grand Prairie's foundation repair permit asks the engineer's letter to say whether plumbing will need testing, and it requires separate permits for water, sewer or gas line repairs.
- On the record: Kennedale's January 2023 permit report includes a plumbing permit for a sewer slab leak repair, valued at $5,905. Slab leak work gets permitted like other plumbing.
Which to call first
If you suspect a leak, a plumber's leak test is the cheaper first step. If the plumbing is sound and the cracks keep growing, that points back to the soil and the foundation. If both are in question, tell the foundation contractor about the leak test up front. Our cost page covers foundation repair prices.
Questions people ask
How much does slab leak detection cost?
Fixr lists $100 to $400 for leak detection, and an average slab leak repair of $2,500, with most between $1,000 and $4,000.
Can a slab leak cause foundation problems?
A leaking line under a slab puts water into the soil beneath the foundation, and Fixr lists new foundation cracks among the signs of a slab leak. A plumber's leak test is a cheap way to rule it in or out.
Do I need a permit to fix a slab leak?
Usually it's permitted as plumbing work. Grand Prairie requires separate permits for water, sewer or gas line repairs done with a foundation repair. Check with your city.
Have a contractor take a look
Fill in the form or call us. We pass the request to a local foundation repair contractor, and it costs homeowners nothing.
Calls that go to voicemail: leave your name, number, the property address and what you've noticed.