Signs of a Slab Leak in a Raleigh-Area Home

What exactly counts as a slab leak?

A slab leak is a leak in a water or drain line that runs under or inside a concrete foundation. If your house or townhome in Raleigh, Cary, Morrisville or Holly Springs sits on a concrete slab, some of its supply lines may be buried beneath the floor. When one of those lines develops a pinhole or a failed joint, the water has nowhere obvious to go, so it can run for weeks before anyone notices.

There are two kinds, and they behave differently:

• Supply line leaks are under constant pressure, so they leak all the time. They spin the water meter and raise the bill. If the hot line is leaking, it can also warm the floor and keep the water heater running.
• Drain line leaks only leak when water goes down the drain. They do not move the meter, but they can cause odors, slow drains and damp soil under the slab. A camera inspection of the drain is the usual way to confirm these.

Which warning signs should I look for?

No single clue proves a slab leak, but two or three together are worth a call.

Pressure problems have many other causes, so if that is your only symptom, start with the guide to weak water pressure first.

How can I test for a leak myself?

The EPA's WaterSense program suggests a simple meter test. Here is how to do it on a Raleigh Water meter:

1. Turn off every faucet, the dishwasher, the washing machine, the ice maker and any irrigation.
2. Open the meter box lid at the street and note the reading. Many meters also have a small leak indicator that spins with even a little flow.
3. Wait two hours without using any water, then read it again.
4. If the reading changed at all, EPA says you probably have a leak.

Next, rule out the easy stuff. Toilets are an easy place to start. Put a few drops of food coloring in the tank, wait 15 minutes without flushing, and see if color shows up in the bowl. Check outdoor spigots and the irrigation backflow assembly too.

If the toilets and fixtures are fine and the meter still moves, close the main shutoff inside the house. If the meter stops, the leak is inside the home, which points toward the slab or walls. If it keeps moving with the main closed, the leak is likely in the yard line between the meter and the house, which is a service line repair rather than a slab job.

EPA puts average household leaks at more than 9,300 gallons a year and says 9 percent of homes have leaks wasting 50 gallons or more a day, so a moving meter is worth chasing even if the bill increase looks small.

How do plumbers pinpoint a leak under concrete?

Good leak location keeps the repair small. A specialist typically isolates hot and cold lines to see which one is losing pressure, then uses acoustic listening equipment to hear the leak through the floor, sometimes with thermal imaging to spot a warm trail from a hot line. Some technicians add tracer gas to a drained line and sniff for it at the surface. The goal is to mark a spot within a foot or two before anyone opens the floor.

HomeAdvisor's June 2026 cost guide says most homeowners pay $150 to $400 for slab leak detection. Fixr's May 2025 guide gives a similar $100 to $400. If you want this done, look for electronic leak detection in Raleigh as a first step rather than calling for demolition.

What are the repair options, and what do they cost?

Once the leak is found, there are three main approaches. Costs vary with flooring, access and how many lines are failing.

HomeAdvisor puts the average total slab leak repair at $2,280, with most projects between $630 and $4,400. The two guides disagree sharply on rerouting, which reflects how much the scope can change: rerouting one hot line in a small home is a different job from replacing all the plumbing in a large one. Get the scope in writing.

Direct access makes sense for a single, well-located leak in a newer system. If a home has had more than one leak or the pipe shows widespread corrosion, many plumbers will suggest rerouting or replacing the supply lines instead of patching one spot at a time. Budget separately for flooring. Breaking concrete under tile or hardwood means that flooring has to be removed and replaced, which is often the largest part of the bill.

For a closer look at how these jobs are handled locally, see slab leak repair in Raleigh, or the town pages for slab leaks in Holly Springs and Morrisville plumbers.

How urgent is a slab leak?

It depends on what you see. A slow pinhole caught on the meter test is not a middle-of-the-night emergency, but it should not be left for months either. Water under a slab can soften soil, encourage mold under flooring and keep running up your bill. Treat it as urgent if water is surfacing through the floor, flooring is lifting, or you hear a steady rush of water. In that case, close the main shutoff and arrange help. You can turn the water back on briefly for essentials until the repair.

Will Raleigh or my insurance help with the cost?

Raleigh treats underground and in-wall leaks as non-accessible, and its leak adjustment program can adjust both water and wastewater charges to double your monthly average for those leaks. You need usage of at least twice your average, a plumber's receipt or other proof of repair, and you can receive only one adjustment in 12 months. Leaks covered by insurance are excluded.

Homeowners policies vary. Many cover the resulting water damage and the cost to access the pipe but not the failed pipe itself. Read your policy, and follow the NC Department of Insurance advice to report a loss promptly, photograph the damage and keep receipts.