Slab Leak in San Antonio: Signs, Repair Cost, and How to Get a SAWS Bill Adjustment
A slab leak is a leak in a water or drain pipe that runs in or under your home’s concrete foundation. You usually can’t see it, so the first clue is often a water bill that suddenly jumps. Below: the signs, published repair costs, San Antonio permit rules, and how to ask SAWS (San Antonio Water System) for a credit once the leak is fixed.
On this page
Signs of a slab leak
No single sign proves a slab leak. Common ones, per HomeGuide, Angi and SAWS:
- A water bill that is much higher than usual, with no change in how you use water.
- The sound of running water when every faucet, toilet and appliance is off.
- A warm spot on the floor, which can point to a leak in a hot-water line.
- Damp carpet, warped wood or vinyl, stains, mildew or a musty smell near the floor or baseboards.
- A sudden drop in water pressure.
- New cracks in the foundation or floor.
- Wet or unusually green patches in the yard near the foundation.
Try this first: the 1-hour meter test
SAWS explains how to use your own meter to check for a leak (SAWS meter guide):
- Turn off all water inside and outside, including sprinklers and the ice maker.
- Find the meter box. It is usually under a lid between the front hose faucet and the street. Watch for spiders and ants.
- Tap the button on the digital meter until you reach the Flow Rate screen. Any number other than zero means water is moving.
- For a clearer answer, write down the Current Total Volume, keep all water off for an hour, and check again. A higher number means a leak.
This shows a leak somewhere on your side of the meter, not necessarily under the slab. Rule out toilets first: SAWS suggests food coloring in the tank; if color reaches the bowl without flushing, the toilet leaks.
Whose pipe is it? SAWS maintains the line from the main to the meter. You are responsible for everything from the meter to your home (SAWS). For a water or sewer emergency on the SAWS side, SAWS lists 210-704-SAWS (7297), 24 hours a day.
Why San Antonio slabs move: clay soil
Much of the San Antonio area sits on clay that swells when wet and shrinks when dry. Texas’s state soil, Houston Black clay, covers about 1.5 million acres of the Blackland Prairie, which runs from north of Dallas south to San Antonio. The Texas Water Development Board describes it as a “highly expansive” clay that shrinks and swells markedly with moisture, and notes its shrink-swell potential is a common limitation for building sites (TWDB). When dry, it can crack ½ to 4 inches wide and a foot or more deep (USDA).
When the ground under a slab shrinks and swells, the slab moves a little, and pipes in or under it take the strain. Angi lists expansive soil as one root cause of slab leaks worth fixing along with the pipe (Angi). Other common causes are corrosion, heat and pressure stress on the pipe, and hard or acidic water (HomeGuide). Soil varies from lot to lot, so a slab leak doesn’t always mean a foundation problem, or the reverse.
Repair options and what they cost
A plumber should first find the leak with electronic detection (acoustic listening, pressure tests, thermal imaging). Then there are three main ways to fix it:
- Spot repair: open the floor and the slab right over the leak, fix that section of pipe, and patch the concrete. Most mess in one spot.
- Reroute: leave the bad pipe under the slab, cap it, and run a new line through the walls or attic. No concrete cutting, but some drywall holes.
- Repipe: replace the water lines for the whole house, usually overhead. Costs most up front; often suggested after repeat leaks.
| Item | Published range | Source |
|---|---|---|
| Leak detection | $150–$400 (average about $280) | Angi, 2026 |
| Typical slab leak repair, detection included | $630–$4,400 (average about $2,280) | Angi, 2026 |
| Spot repair: breaking the slab | $500–$3,000, plus $250–$800 to patch | HomeGuide |
| Reroute | $600–$4,000 (extensive reroutes can pass $10,000) | Angi, 2026 |
| Reroute (second source) | $3,900–$7,500 | HomeGuide |
| Whole-house repipe | $1,500–$15,000 (most pay about $7,500) | Angi, 2026 |
| Texas check: one Austin plumber’s published ranges | Spot $1,200–$3,500 · Reroute $2,000–$5,500 · Repipe $5,000–$15,000 | Ironclad Plumbing |
| Putting floors back (build-back) | $300 to $10,000+, depending on flooring and cabinets | Angi, 2026 |
Two things move the price most: access (a leak under a utility closet costs far less than one under kitchen cabinets) and build-back (tile and wood floors are expensive to replace). Angi notes water damage from a long-running leak can add $500 to $15,000 or more.
Insurance: policies differ. Angi notes that many policies cover leaks caused by a covered event, such as pipes freezing and bursting, but may not cover leaks from corrosion. Call your insurer before tear-out and take photos.
Do you need a permit in San Antonio?
Often, yes. San Antonio’s building code (City Code Chapter 10, 2024 codes adopted in January 2025) exempts simply stopping a leak. But if a concealed pipe is defective and has to be removed and replaced with new material, the code treats that as new work that needs a permit and an inspection (Ch. 10 text). Most slab leak repairs and all reroutes replace pipe, so expect a permit.
- In an emergency, the code says the permit application must be filed by the next business day.
- A licensed plumber normally pulls the permit. The City’s only homeowner exception is a homeowner working personally on the homestead they live in (DSD Residential Permits).
- Cibolo, Schertz, Helotes and other nearby cities have their own permit offices.
How to ask SAWS for a leak bill adjustment
SAWS may credit part of the extra water from a leak that has been repaired. “Broken pipe (in wall, foundation, yard, etc.)” is on its list of eligible leaks. Steps from SAWS’s leak adjustment page:
- Fix the leak first. SAWS only reviews leaks that are already repaired.
- Get proof. A licensed plumber’s receipt is the clearest proof. SAWS also accepts receipts for supplies you installed yourself, or a detailed repair description. You can upload one file, so pick the most complete receipt.
- Apply within 60 days of the repair. Log in to your SAWS account (or create one), choose “Other Services,” and start a leak adjustment. Send one request per repair.
- Wait for review, up to 30 days. Your account goes on hold (no late fees or disconnection). Keep paying at least your average pre-leak bill.
- SAWS checks that your usage dropped. If it did, SAWS adjusts a portion of the leak water for up to two months.
Good to know: SAWS says it has no legal obligation to grant an adjustment, and it does not pay for the plumbing repair. A SAWS spokesperson told KENS 5 that bills are adjusted for leaks once per year. If your water bill does not come from SAWS, ask your own utility about its leak policy.
Questions to ask a plumber
- Can you show me where the leak is before you open the floor? Is it a hot or cold line, supply or drain?
- Which do you recommend for my house, spot repair, reroute or repipe, and why?
- Can I get a written, itemized quote that lists detection, repair, concrete patch, drywall and any flooring work separately?
- Will you pull the City permit and schedule the inspection? Is the fee in the quote?
- What is your Texas plumbing license number? (Then look it up yourself at tsbpe.texas.gov.)
- What does your warranty cover, and for how long?
- Will your receipt show the date, address, leak type and location, and the repair done, so I can send it to SAWS?
- Will you pressure-test the line after the repair?
Find a plumber for a slab leak in San Antonio
Browse plumbers listed by area: Central San Antonio, East San Antonio, North San Antonio, Northeast San Antonio, South San Antonio, West San Antonio. Ask each one whether they do leak detection, reroutes and repipes, and get a written estimate.
Listings are not endorsements, and this directory does not check licenses for you. Check any license at tsbpe.texas.gov.
FAQ
How do I know if I have a slab leak?
Watch for a sudden jump in your water bill, running-water sounds when everything is off, a warm floor spot, damp flooring or low pressure. The SAWS meter test shows whether water is moving; a plumber with detection equipment can find where.
How much does slab leak repair cost?
Angi’s 2026 data puts typical repair at $630 to $4,400 (average about $2,280, detection included). Reroutes run $600 to $4,000 (Angi) or $3,900 to $7,500 (HomeGuide); a whole-house repipe averages about $7,500 (Angi). Flooring is often extra.
Does SAWS pay for slab leak repair?
No. After the leak is fixed, SAWS may credit part of the leak water for up to two months if your usage drops.
How long do I have to ask SAWS for a leak adjustment?
Within 60 days of the repair. Review can take up to 30 days.
Do I need a permit to fix a slab leak in San Antonio?
Usually. Replacing a defective concealed pipe counts as new work that needs a permit and inspection under the City code.
Sources
- SAWS – Request a Leak Adjustment (read Oct 26, 2026)
- SAWS – Reading your water meter to find leaks
- Angi – Slab leak repair cost, 2026 data (updated Sep 22, 2026)
- Angi – Cost to repipe a house, 2026 data (updated Aug 3, 2026)
- HomeGuide – Slab leak repair cost
- Ironclad Plumbing (Austin) – Slab leak repair options
- City of San Antonio – Chapter 10 building-related codes (2024)
- City of San Antonio DSD – Residential permits
- Texas Water Development Board – Houston Black, Texas state soil
- USDA – Houston Black soil series description
- KENS 5 – “Woman gets $600 water bill. Does SAWS have a policy to fix it?”
General information only. This page is not legal, insurance, engineering or plumbing advice. SAWS rules, City codes and prices change, so confirm with SAWS, your city and your plumber. Check any plumber’s license at tsbpe.texas.gov before you hire.