A hot water slab leak is a pinhole or split in a hot supply line that runs through or under the concrete floor of the house. Because the pipe is buried, the price is driven less by the pipe itself and more by the work needed to reach it and close the floor afterward.
That is why two neighbors can get very different quotes for what sounds like the same problem. The sections below walk through the factors in the order they usually come up on a job.
How do you know the leak is hot water and under the slab?
Hot lines fail under a slab for a few common reasons. Heat expands and contracts the pipe every time the water heater cycles, and copper that rubs against concrete or a sleeve can wear through over time. Aggressive water can also pit the pipe wall from the inside.
The usual signs are a floor that feels warm in one spot, the sound of running water when every fixture is off, and a water heater that seems to fire again and again. Wet carpet edges or lifting laminate near a wall are another clue.
A quick check you can do yourself
Turn off every tap and appliance. Find the water meter and watch the small leak indicator, often a triangle or dial. If it keeps moving, water is going somewhere.
Then close the shutoff valve on the cold inlet at the top of the water heater. If the meter stops, the leak is on the hot side.
Hot spot on the floor or a water heater that never stops running? Call (855) 575-2890 and ask for a clear price before any concrete is cut.
Call (855) 575-2890What actually sets the price of the repair
Every slab leak quote is built from the same handful of parts. Understanding them lets you compare two bids on equal terms instead of comparing totals alone.
Locating the leak first
Acoustic listening gear, thermal imaging and pressure testing each narrow the search. A tight location means a small opening in the floor. A vague one means more demolition, and demolition is the expensive part.
Access and what covers the slab
Tile, hardwood and carpet all cost different amounts to lift and replace. A leak under a kitchen island or built-in cabinets takes more labor than one in an open hallway.
Spot repair, reroute or repipe
A spot repair opens the slab and fixes one section. A reroute abandons the leaking run and sends new hot lines through the attic or walls. A full repipe replaces the system. Each step up costs more now and may avoid repeat leaks later.
Pipe material and how many leaks
Aging copper often develops more than one weak point, so a second leak found during testing can change the plan from a patch to a reroute. Newer PEX behaves differently and is easier to run overhead.
Permits, inspection and restoration
Rerouted or changed plumbing may need a permit, which adds paperwork and an inspection. Concrete patching, drywall, paint and flooring are often priced separately from the plumbing itself.
On insurance, a sudden burst or accidental discharge is often covered, while wear, corrosion and slow leaks often are not. Policies differ, and some cover the damage but not the pipe itself, so read your policy or ask your agent before work begins. Take photos of everything first.
Want your real number? Call (855) 575-2890. We give a clear price before work starts.
Spot repair versus reroute: which fits your leak?
There is no single right answer. The table below shows how the choices tend to compare, so you can ask better questions when a plumber lays out options.
| Option | Best when | Main cost drivers |
|---|---|---|
| Spot repair under the slab | One leak, pipe otherwise sound, floor easy to open | Concrete cutting, flooring replacement, patch work |
| Reroute through attic or walls | Pipe is old or the leak sits under cabinets or tile | New pipe length, drywall access, permit and inspection |
| Full hot line repipe | Several leaks or pipe failing in multiple places | Total pipe run, number of fixtures, wall repair |
| Leave it and monitor | Never a good plan for a confirmed hot leak | Rising water use, floor damage, mold risk |
Your plumber should explain why one option fits your pipe, and not simply offer the cheapest path.
When to stop and call right away
Most slab leaks are not dramatic, but a few signs mean you should stop waiting and make the call.
Call the same day if you see any of these
- Water or steam rising through a crack in the floor, which can scald bare feet.
- A floor that is too hot to stand on, especially over a hallway or near the water heater.
- Standing water near outlets, a panel, or any appliance. Stay away and shut off power at the breaker only if it is dry and safe to reach.
- A meter that keeps spinning after you shut off every fixture in the house.
- Musty smell, peeling baseboards or swelling flooring along one wall.
Why the water heater is the first thing to check
A hot line leak makes the heater work harder because it keeps refilling with cold water that must be warmed again. If the burner or element seems to run constantly, that is a clue worth giving your plumber.
It also helps to know whether the leak is on the hot line at all. A cold line slab leak is a different repair. Our leak-finding work separates the two before anyone opens the floor, which keeps the repair scoped correctly.
For confirmed leaks under the concrete, slab leak repair covers the spot repair, reroute and repipe choices described above.
What Los Gatos permit and license rules mean for a slab leak
Before work starts, ask who files the permit and whose name goes on it. If a plumber proposes a reroute, ask whether the job needs a permit and who pulls it. Permit rules vary, so check with the Town Building Division before work starts.
The Town accepts permit applications through its online citizen portal, not at the counter, so allow time to register an account. Check any contractor with the License Check tool from the Contractors State License Board (CSLB) before you sign, since it also covers home improvement salesperson registrations. A Town of Los Gatos permit checklist says permits are issued only to the homeowner or a licensed contractor.
If your home sits near the edge of town, the same questions apply. Homeowners in Campbell and Cambrian Park deal with their own city rules, so confirm which jurisdiction your address falls under.
Questions to ask before you approve the work
Ask how the leak was located and how large the opening will be. Ask what the quote includes for flooring and drywall, and what it leaves out.
Ask whether the pipe nearby shows signs of wear, and what happens if a second leak appears next year. A good answer is specific. A vague one deserves a second opinion.
Finally, ask for the price in writing before work starts. A clear scope protects both sides, especially when demolition is involved.
Hot water slab leak cost questions
They often assume different methods. One may be a spot repair under the slab and another a reroute through the attic. Ask each plumber what is included for flooring and wall repair.
It depends on the policy. Sudden accidental discharge is often covered, while corrosion and slow leaks often are not. Some policies pay for resulting damage but not for the pipe, so check yours.
A steady leak is worth fixing soon because it wastes water and can damage the floor. Steam, scalding floors or water near electrical gear is urgent, so call right away.
Sometimes. A reroute through walls or the attic avoids opening the slab. It depends on the layout of the house and where the leaking run sits.
For anything beyond minor work, yes. Ask who files the permit and whose name goes on it, and you can verify a contractor's license with the state board's License Check tool.