The most common slab leak signs are a water bill that jumps without a change in your habits, a water meter that keeps moving when every tap is off, warm spots on the floor, the sound of running water, and damp or warped flooring. If you see them, run a meter test, then call a licensed plumber.
A slab leak is a leak in a water line buried under or inside a home’s concrete slab foundation. Because the pipes are hidden under concrete, these leaks often go unnoticed until they cause visible damage or a high bill. This guide covers what to look for, how to check your meter, what to do first, and how slab leaks are usually repaired. It is general information. Your plumber, your water provider, and your insurance policy have the final word on your situation.
What Is a Slab Leak?
In a slab home, some of the water supply lines run below the concrete floor. When one of those pipes develops a hole or a failed joint, water escapes under the foundation instead of into a cabinet or wall where you might see it. A Family Handyman guide to foundation slab leaks notes that slab foundations are a common construction choice in Southern and Western states with warm climates. It quotes a Texas plumbing contractor naming corrosion, built-up pressure on underground pipes, and abrasion from pipes rubbing against a hard surface as possible causes, and notes that older homes with original pipes are more vulnerable.
A slab leak can be on the cold side or the hot side of your plumbing. The same Family Handyman guide quotes a contractor saying slab leaks are often in hot water lines, which is why a warm patch of floor is one of the better known warning signs.
What Are the Signs of a Slab Leak?
No single sign proves you have a slab leak, but several together are worth checking right away. Watch for:
- A higher water bill when your water use has not changed.
- The flow indicator on your water meter moving while all water in and around the house is turned off.
- A text, call, or letter from your water provider about continuous water use.
- Warm or hot spots on the floor, often noticed when pets start lying in one spot.
- The sound of running or rushing water when no faucet, toilet, or appliance is running.
- Damp carpet, stained carpet, or a musty or sour smell with no visible source.
- Wood or vinyl flooring that warps, lifts, or separates.
- New cracks in walls or floors.
- Water pooling outside near the foundation.
The Family Handyman guide lists unexplained water bills, cracks in walls and floors, pooling water, mold and mildew under carpets, hot spots on the floor, and the sound of running water as signs of a foundation slab leak. Some of these, like cracks or a musty smell, have other causes too, which is why the next step is a meter test rather than a guess.
How Do I Check My Water Meter for a Hidden Leak?
Your water meter is the simplest tool you have. The Las Vegas Valley Water District’s find and fix leaks page calls the meter the main tool for finding out whether you have a leak. Its steps for the main service line are:
- Turn off all water inside and outside your home, including irrigation, then check the red or white flow-indicator triangle on your water meter. If it is still moving, you may have a leak.
- Find your water shutoff valve, which the district says is usually in your front yard near the sewer riser cap, in your garage, or in your home’s manifold system, and make sure it is off.
- Check the flow indicator again. If it is still moving, the leak is most likely underground between the shutoff valve and the meter. If it has stopped, the leak is somewhere else around your home.
That last result matters for slab leaks. If the indicator stops when the house shutoff is closed but moves when it is open and nothing is running, water is going somewhere past the shutoff, which includes the lines under the slab, as well as toilets, faucets, a water softener, or other fixtures. The district’s page also walks through isolating irrigation, toilets, faucets, softeners, and pools so you can rule those out. LVVWD says most residential meters are located near the front yard or in the front sidewalk. When you finish, close the meter cap and replace the box lid, as the district advises.
The EPA’s WaterSense program suggests a similar check in its Fix a Leak Week guidance: read your water meter before and after a two-hour period when no water is being used. If the meter changes at all, you probably have a leak.
LVVWD also cautions that troubleshooting leaks yourself carries a risk of injury or property damage. Do not open meter boxes or valves you are not comfortable with, and never break into concrete to look for a leak.
Does the Water District Tell You About Leaks?
Sometimes. LVVWD says that with its advanced metering technology, it reaches out to account holders when continuous water flow is detected through the meter at a property for at least three days. If you get one of those notices, treat it as a reason to do the meter test above. The district also notes on its high bill page that a sudden bill increase when you have not changed your water use may mean you have a leak, and that most significant increases in water use happen in summer when landscape watering goes up. Ruling out irrigation first keeps you from chasing a slab leak that is really a broken sprinkler line.
What Should I Do First If I Suspect a Slab Leak?
- Run the meter test so you know whether water is flowing when it should not be.
- Note what you are seeing, such as warm spots, damp areas, sounds, and the dates of any high bills, with photos where you can.
- If water is visibly coming up into the house or the leak seems large, close the main shutoff valve until a plumber arrives.
- Move rugs, furniture, and belongings off damp flooring and start drying what you can.
- Call a licensed plumber for leak detection, and contact your insurance company if there is damage to the home.
Speed matters because of what water does to a house. The EPA’s guide to mold and moisture says it is important to dry water-damaged areas and items within 24 to 48 hours to prevent mold growth, and it lists the underside of carpets and pads and areas inside walls around leaking pipes among the places mold can hide.
How Do Plumbers Find a Slab Leak?
A slab leak is not always under the spot where water shows up, as the Family Handyman guide points out. Plumbers start by confirming a leak exists, then work out which line is leaking and where along its run, using specialized leak detection equipment so they open as little of the floor as possible. Pinpointing the location first is what makes it possible to compare repair options instead of breaking up the floor to search.
Butler’s Construction offers leak detection in Las Vegas, from minor pipe leaks to slab leaks, using modern equipment to find and repair leaks quickly and accurately.
How Is a Slab Leak Repaired?
There is no single right answer. The best repair depends on where the leak is, the age and condition of the rest of the piping, the flooring above it, and whether this is the first leak or one of several. The common approaches described in the Family Handyman guide are:
- Reroute the line. A new pipe is run through walls, ceilings, or the attic to bypass the leaking section, which is abandoned in place. The guide quotes a contractor calling this often the cheapest and least disruptive fix, though it means opening some drywall.
- Direct repair through the slab. The plumber breaks through the concrete above the leak, repairs the pipe, and patches the floor. It is targeted, but it is disruptive inside the house and means replacing the flooring over the spot.
- Repair from under the slab. In some parts of the country, crews tunnel under the home to reach the leak. It is less destructive inside but can cost more depending on where the leak is.
- Reline the pipe. The inside of the pipe is coated to seal it. The guide notes this works best for small leaks.
- Reroute or reline the whole house. If the pipes are deteriorating or there have been multiple leaks, a whole-house reroute or relining may make more sense than fixing one spot at a time.
Ask your plumber why the leak happened before you choose. A one-off failure, such as a pipe rubbing against a rock, points toward a spot repair or a single reroute. Widespread corrosion points toward a whole-house solution. Our water line repair team can advise whether a spot repair or a repipe makes more sense for your home.
What About the Damage the Leak Already Caused?
Fixing the pipe stops new water, but it does not dry the slab, the flooring, or the walls that got wet. Depending on how long the leak ran, you may need water extraction, drying, and replacement of flooring, baseboards, cabinets, or drywall. That restoration work is a separate scope from the plumbing repair, so ask about both. Butler’s handles water damage restoration, including extraction, drying, repairs, and mold prevention, along with the plumbing work.
Does Homeowners Insurance Cover Slab Leaks?
It depends on your policy, so check your policy and talk to your agent or insurer before assuming either way. Coverage generally turns on what caused the damage and how the policy is written. The Nevada Division of Insurance’s 2026 Consumer’s Guide to Home Insurance explains that dwelling coverage includes fixtures such as plumbing, and it lists accidental discharge, leakage, or overflow of water from within a plumbing system among the perils covered by common policy forms. The Insurance Information Institute notes that a standard policy will not pay for damage caused by routine wear and tear.
Two practical points. Ask your insurer how your policy treats the cost of repairing the pipe itself versus the damage to floors and walls, and keep photos and invoices. For the separate service line that runs from the meter to the house, LVVWD says leaks are typically not covered by homeowners insurance, which is why the district offers account holders an optional water line warranty through a third party.
Can the Las Vegas Valley Water District Help With the Cost?
LVVWD runs several customer assistance programs for leaks. Eligibility rules apply to each, so read the current details on the district’s page before you count on one. As of October 2026, the district describes:
- Leak Adjustment Program: customers with an unusually high bill caused by a leak may qualify for an adjustment after the leak is repaired. Requirements include water use rising at least 50 percent over a baseline month, repairs completed within 60 days of the billing date when the leak was discovered, and an online application within 90 days of the repair.
- Leak Repair Reimbursement Program: single-family residential property owners may be reimbursed up to 50 percent of the cost to repair a leak, up to $2,000 per event, with a paid invoice. Tenants are not eligible, and the minimum repair amount is $200.
- Low-income Leak Repair Assistance: income-eligible homeowners served by LVVWD could qualify for up to $10,000 per leak event through community partners, which take the applications directly.
- SNWA Leak Detection Assistance Program: eligible single-family residential customers can get a voucher of up to $250 toward professional leak detection, used with a participating SNWA Water Smart Plumber.
The Southern Nevada Water Authority’s Leak Detection Assistance Program page explains that the voucher covers the initial diagnostic visit or the first two hours of repair work, is limited to one per qualifying property per calendar year, and only works with plumbers who participate in the voucher program. Save your paid invoices and photos either way, because both programs and insurers ask for documentation.
Can You Prevent Slab Leaks?
You cannot see or maintain pipes buried under concrete, so prevention is mostly about catching leaks early. Check your water bill every month for unexplained increases, run a meter test now and then with everything off, and pay attention to warm spots, damp flooring, and unfamiliar sounds. LVVWD’s My Account lets you monitor daily water usage and compare trends, which the district says can reveal unexpected changes that may be an early sign of a leak. The district also points homeowners to an SNWA rebate coupon for home leak sensors that send alerts to your smartphone.
How Butler’s Construction Handles Slab Leaks
Butler’s Construction is a licensed Nevada general contractor and C-1 plumbing contractor serving the Las Vegas valley. Our team can find the leak, explain the repair options for your home, fix the line, and restore floors and walls afterward, so you deal with one contractor from detection through the final walkthrough.
If your meter is moving with everything off, or you are seeing any of the signs above, call us or request a free estimate.
Sources
- Las Vegas Valley Water District: Find and Fix Leaks in Your Home
- Las Vegas Valley Water District: Customer Assistance Programs
- Las Vegas Valley Water District: High Bill
- Las Vegas Valley Water District: Water Meter
- Southern Nevada Water Authority: Leak Detection Assistance Program
- Southern Nevada Water Authority: Water Leaks
- EPA WaterSense: Fix a Leak Week
- EPA: A Brief Guide to Mold, Moisture and Your Home
- Nevada Division of Insurance: 2026 Consumer’s Guide to Home Insurance
- Insurance Information Institute: What Is Covered by Standard Homeowners Insurance?
- Family Handyman: Foundation Leak Signs Every Homeowner Should Know