Slab Leak Repair Cost: Detection, Repair and Reroute

Slab leak repair usually costs $1,000 to $4,000, with a national average of $2,500 (Fixr). Finding the leak first costs $100 to $400 (Fixr). Rerouting the pipes instead of repairing them costs more, and rerouting every line can reach $15,000 (Fixr).

A slab leak is a leak in a water or drain pipe that runs under a concrete foundation. This guide covers what detection costs, what each repair method costs, how a plumber chooses between them, and what to ask. Every figure is a national range from the page it links to. Prices near you may differ.

What should you do first if you suspect a slab leak?

A slab leak is rarely a gushing emergency, but it can do steady damage. Take these steps:

• Turn off the main water valve if you see water coming up through the floor or the leak is getting worse. The main shut-off is usually where the main line enters the house: a basement, crawl space, garage, utility room or outside near the meter.
• Stay clear of water near outlets, cords or appliances. Don't touch anything electrical while standing in water. If you'd have to walk through water to reach the main power switch, leave it for an electrician.
• Call your insurance company before repairs start. Fixr says slab leaks are usually not covered by homeowners insurance, though this varies by policy and region. It advises calling your insurer first, because trying to claim repairs afterward usually results in a denial.
• Take photos of any warm spots, damp flooring, cracks or water bills that jumped.

What are the signs of a slab leak?

Fixr lists these common signs:

• The sound of running water when no fixtures are on
• A water bill that's higher without more use
• Low water pressure
• Cracks in the foundation
• Musty or bad smells
• Mold on walls or floors above the slab
• Puddles, or patches of unusually green grass and plants in the yard

Warm spots on the floor can point to a leak in a hot water line under the slab.

How can you check for a leak yourself?

You can do a simple meter test before calling anyone:

1. Turn off every faucet, appliance and fixture that uses water, including the ice maker and irrigation.
2. Find your water meter and note the reading, or look for a small leak indicator dial.
3. Wait an hour or two without using any water.
4. Check the meter again.

If the reading changed with nothing running, water is going somewhere. It could be a running toilet, a leaking faucet, an outdoor line or a slab leak. Check toilets first: the EPA suggests putting a few drops of food coloring in the tank, and if color shows up in the bowl after 10 minutes, the toilet is leaking (EPA WaterSense has the full steps).

If toilets and faucets are fine and the meter still moves, a plumber can test further.

How much does slab leak detection cost?

Before anyone breaks concrete, a plumber needs to find the leak. Fixr says detection costs $100 to $400, depending on how invasive it needs to be (Fixr).

Fixr says an inspection typically takes 1 to 3 hours. Plumbers may use:

• Pressure tests to find which line is losing water
• Acoustic listening tools to hear water escaping under the floor
• Thermal cameras to spot warm areas from a hot water line

Good detection matters. The more precisely the leak is found, the smaller the hole in your floor and the lower the repair bill.

Fixr puts the low end of a full slab leak job at $600, for leak detection and a small epoxy repair (Fixr).

How much do the different repair methods cost?

Once the leak is found, there are several ways to fix it. Fixr gives these average costs, labor included:

• Breaking the slab (direct access): $500 to $3,000 (Fixr)
• Tunneling under the slab: $900 to $2,000 (Fixr)
• Pipe lining: $500 to $2,000 (Fixr)
• Broken pipe repair with epoxy: $200 to $2,000 (Fixr)
• Sealing: $100 to $200 (Fixr)
• Rerouting the line: $4,000 to $15,000 (Fixr)

This Old House lists slab leak repair at $500 to $4,000 (This Old House), and rerouting plumbing at $700 to $1,500 (This Old House). The gap between sources reflects how much the job depends on how many lines are moved and how far.

Direct access: breaking the slab

The plumber cuts or jackhammers through the floor right above the leak, repairs the pipe, then fills the hole with concrete. It's the most direct fix.

Fixr says slab breaking is usually the answer when a trenchless sleeve isn't possible and tunneling under the home isn't possible either. Fixr estimates breaking the slab and repairing the pipe below may take 1 to 2 days.

The catch is your floor. Whatever flooring sits over the leak has to come up, and may not go back down cleanly.

Tunneling

The plumber digs from outside the house and tunnels under the foundation to reach the pipe. Nothing inside the house is torn up.

Fixr says tunneling can only be done where the soil is stable enough to support it, and may take 4 to 6 hours.

Pipe lining and epoxy

A liner or epoxy coating is put inside the existing pipe to seal it from within. Fixr says trenchless repairs are the fastest and can be done in a couple of hours.

Lining works best when the pipe is in fair shape overall. If the pipe has many weak spots, a pro may recommend another method.

Rerouting

Instead of fixing the pipe under the slab, the plumber abandons it and runs a new line through the walls, ceiling or attic. Fixr says rerouting is often the answer when there's more than one pipe problem under the slab, and that the new pipes usually run through the attic. Fixr also says rerouting takes the longest.

Rerouting costs more up front. But if the pipes under the slab are old and failing, it can save you from paying for the next slab leak.

What else can add to the cost?

The pipe repair is only part of the bill. Ask about these:

• Labor. Fixr says plumbers charge $45 to $200 an hour for slab leak work, and most people pay $75 to $130 an hour (Fixr).
• Labor over a longer job. Fixr says the repair can take from 2 hours to 3 days, so labor alone could run $90 to $4,800 (Fixr).
• Patching the slab: $250 to $800 (Fixr)
• Water-damaged subfloor: $500 to $1,000 (Fixr)
• Replacing a concrete slab: $4,000 to $8,000 (Fixr)
• Flooring. Fixr notes that flooring may need to be removed before the slab is broken. Sometimes it can be saved and put back, and sometimes it can't.
• Drywall and paint. Rerouting means opening walls or ceilings, which then need patching.
• Water damage cleanup. If water has soaked into walls, cabinets or flooring, drying and repair may be a separate job.

Ask the plumber which of these the quote includes, and which you'd need to arrange separately.

What causes slab leaks?

Fixr names these common causes:

• Expansive soils. Soil that soaks up water swells, pressing on the slab and pipes.
• Pressure from soil movement. Shifting soil can crack pipes.
• Older pipe materials. Older galvanized steel, cast iron and copper can corrode.
• Water chemistry. Acidic water can corrode some pipe materials over time.

Knowing the likely cause helps you decide between a spot repair and a reroute. If the pipes are old and the soil keeps moving, another leak may follow.

Should you repair the leak or reroute the pipes?

This is the biggest decision in a slab leak job. A pro will look at your situation, but these points help you think it through.

A spot repair often makes sense when:

• It's the first slab leak in the home.
• The pipes are newer and in good shape apart from the leak.
• The leak is easy to locate precisely and reach.
• The flooring over the leak is easy to lift or replace.

Rerouting often makes sense when:

• There has been more than one slab leak.
• The pipes under the slab are older or corroding.
• The leak is under expensive or hard-to-replace flooring, or under cabinets.
• The plumber finds more than one problem under the slab.

For a home with many failing lines, a plumber may suggest repiping the whole house. Fixr puts the cost to replace the plumbing in an average 2,000-square-foot house at $4,000 to $12,000 (Fixr). This Old House lists whole-house plumbing at $10,000 to $20,000 (This Old House).

What happens on the day of the repair?

Knowing what to expect helps you plan, especially if you'll be without water for a while. Most slab leak jobs follow these steps:

1. The water is shut off. The plumber turns off the main valve, or just the affected line if the home's plumbing allows it.
2. The work area is prepared. For a direct-access repair, furniture is moved and the flooring over the leak is lifted. For tunneling, digging starts outside. For a reroute, the plumber plans a path through walls, ceilings or the attic.
3. The pipe is reached and repaired. The damaged section is cut out and replaced, sealed from inside, or bypassed with a new line.
4. The line is tested. The plumber turns the water back on and checks that the repaired line holds pressure with no leaks.
5. The opening is closed. The hole in the slab is filled with concrete, the tunnel is backfilled, or the wall openings are closed for patching.
6. Restoration follows. Flooring, drywall and paint may be handled by the same company or by someone else. Ask before work starts so you're not surprised.

Plan for dust and noise if the slab is being broken, and keep children and pets away from the work area. If you have important items stored near the leak, move them before the plumber arrives.

Is a slab leak a foundation problem?

Not necessarily. A slab leak is a plumbing problem, but water leaking under a foundation for a long time can affect the soil underneath. Fixr lists foundation cracks as one sign of a slab leak. If you see new cracks, doors that stick, or floors that slope, mention it to the plumber. They may suggest having the foundation looked at separately once the leak is fixed.

Will homeowners insurance pay for a slab leak?

It depends on your policy. Fixr says that in most cases slab leaks are not covered by homeowners insurance, but that this varies by policy and region.

Policies differ on what they treat separately: the pipe itself, the work to reach it, and any water damage. That's why Fixr advises calling your insurer before work starts. Ask:

• Is the pipe repair covered?
• Is the cost of breaking and patching the slab covered?
• Is water damage to floors, walls or cabinets covered?
• Do you need to approve the repair method or the company first?
• What's the deductible?

What questions should you ask for a fair quote?

Slab leak quotes can vary a lot. These questions help you compare them:

1. How did you find the leak, and how sure are you of its location?
2. How will you find the leak without opening more floor than needed?
3. Which repair method do you recommend, and why that one over the others?
4. Would rerouting make more sense in my home? What would it cost?
5. Does the price include patching the slab, flooring, drywall and paint?
6. How long will the water be off?
7. Will this job need a permit, and will you pull it?
8. Is your work guaranteed, and for how long?
9. Are you licensed and insured for this work in this state?

Get the price in writing, with detection, repair and restoration listed separately. For a job this size, it's normal to get more than one quote.

If you're not sure whether you have a slab leak or something simpler, answer a few short questions to see the likely causes and typical costs: Check my plumbing.

How does this compare with other plumbing costs?

A slab leak is one of the more expensive plumbing repairs. For hourly rates, service fees and the cost of other common jobs, see the plumber cost guide. If water is pooling near a water heater rather than coming up through the floor, the water heater repair vs. replacement guide may help. And if the meter test points to a toilet instead, the toilet repair cost guide covers those fixes.

The bottom line

Most slab leak repairs cost $1,000 to $4,000 (Fixr), after detection that costs $100 to $400 (Fixr). Rerouting costs more but may be the better choice if the pipes under your slab are old or have leaked before.

Start with the meter test, call your insurer before work begins, and ask each plumber to explain how they found the leak and why they recommend one method over another.