$400 to $4,000. What decides where you land is which pipe failed. A water line leak that can be located and repaired or rerouted sits at the bottom of that range. A drain line that has broken under the slab sits at the top, because reaching it is a tunneling job rather than a repair.
Two houses with identical symptoms — a meter that will not stop turning, a warm patch on the floor, a water bill that jumped — can land at opposite ends of that range for that reason alone.
Why we publish a range and not a price. Nobody can price this job from a web page, and any site that gives you one number is guessing. What we can do is tell you the band our own jobs actually land in, what pushes a job to each end of it, and what we would need to see to give you a real number. That is what this page does.
Why is a drain line so much more than a water line?
It is entirely about how you get to the pipe.
A water line under a slab is pressurised, which makes it findable, and it can often be repaired at the failure or rerouted overhead rather than chased through concrete. That is the small end of the job.
A drain line is not pressurised, sits lower, and when it fails it has to be physically reached and replaced. Under a slab house that means tunneling — digging in from outside and working underneath the house. It is more excavation, more days, and more restoration afterwards.
The same symptom can be a straightforward repair or a tunneling job. Which pipe failed is what decides it, and that is knowable before anybody breaks concrete.
Do you have to break up my floor?
It is our last choice, and usually it is avoidable. Tunneling from outside means the work happens underneath the house instead of through the middle of it: no concrete broken inside, no dust through the living areas, and you are not living in a construction site while it happens.
It is not free — it is excavation, and it takes longer than cutting a hole in a floor. What it protects is the inside of your house, and for most people that is the right trade.
Is finding the leak charged separately?
Locating it is part of doing the job properly, not a line item we surprise you with afterwards. The important part is the order: find it, then fix it.
What we will not do is start breaking concrete to go looking, and if anybody proposes that to you, get a second opinion. Locating the leak accurately is exactly what keeps the repair at the small end of the range instead of the large one. See leak detection.
Will insurance pay for it?
Frequently it covers the damage the water did and not the pipe that did it — but policies vary, wording matters, and how the claim is described matters more than people expect.
It is complicated enough that we wrote it up separately rather than compressing it into a sentence here: is a slab leak covered by insurance? Worth reading before you file, not after.
What happens if I leave it?
It gets more expensive, and not linearly. A slab leak is clean water running under your foundation continuously, every hour, and it does not scab over. It washes out the soil supporting the slab, which is how a plumbing problem turns into a foundation problem.
The pipe is rarely the expensive part of a slab leak. What the water did while nobody knew about it is.
How do I know that is what I have?
The usual signs: the water meter turning with everything in the house shut off, a warm spot on the floor, a water bill that jumped without an explanation, the sound of water running when nothing is on, or a patch of floor that stays damp.
We wrote both halves of that up in detail — how to know if you have a slab leak and what causes one. If two or three of those are true at your house, call us before it gets more expensive. We answer 24 hours.
Common questions
How much does slab leak repair cost?
Between $400 and $4,000 for us, and the biggest single factor is which pipe is leaking. A water line leak that can be reached and repaired is at the bottom of that range. A failed drain line under the slab, which means tunneling, is at the top.
Why does a drain line cost so much more than a water line?
Because of how you get to it. A water line can often be rerouted or repaired with limited opening up. A broken drain line under a slab has to be physically reached, and that means tunneling in from outside so the work happens underneath the house rather than through the middle of your floor.
Is finding the leak a separate cost?
Locating it is part of the job rather than a bolt-on we spring on you afterwards. What we will not do is start breaking concrete to go looking. Finding it first is what keeps the repair at the small end of the range.
Will my insurance cover it?
Often it covers the damage the water did and not the pipe itself, but policies vary and the wording matters. We wrote a separate guide on it because the answer is genuinely complicated and worth reading before you file.
Do you have to jackhammer my floor?
Usually not, and it is our last choice. Where a line has failed under the house we tunnel in from outside so the work happens underneath rather than through your floor - no concrete broken inside, no living in a construction site.
Can I just leave it if it is small?
No. A slab leak is water running under your foundation continuously. It does not stay small, it does not stop, and the damage it does to the slab and the soil under it is the expensive part, not the pipe.
Last updated · written by a licensed master plumber, MPL 38224