Slab Leak Detection ProsSlab Leak Detection San Marcos: Exact Spot, Written Report
Slab leak detection San Marcos homeowners and landlords use has to be quick and well documented. San Marcos slab leak detection pinpoints leaks in student rentals near Texas State University, older homes close to the San Marcos River and the newer subdivisions along I-35.
- Acoustic listening
- Thermal imaging
- Tracer gas
- Pressure & hydrostatic tests
- Camera inspection
Slab Leak Detection San Marcos: What We Cover
We do one thing: find leaks under concrete slabs. Every visit is done by an independent, licensed Texas plumber who specializes in leak detection, so you pay to find the leak, not to break concrete searching for it.
Water Line Leaks
Find leaks in the pressurized supply lines buried in or under your slab.
Hot-Water Line Leaks
Thermal imaging traces warm spots and leaking hot-water runs.
Drain Line Leaks
Hydrostatic and isolation tests find drain leaks that never show on your meter.
Pressure Testing
Confirm a leak exists and measure how fast the line loses pressure.
Line Isolation & Tracing
Separate hot, cold and branch lines and map where they really run.
Acoustic Pinpointing
Ground microphones hear escaping water through the concrete.
Tracer Gas Detection
For very quiet leaks and plastic pipe, gas rises at the leak point.
Written Leak Report
Exact location, readings and photos for your insurer or water utility.
Warning signs of a slab leak in your San Marcos home
- Water bill jumped with no change in use
- Meter keeps moving with everything off
- Warm spot on tile, wood or carpet
- Running-water sound when nothing is on
- Water heater runs constantly
- Damp carpet, cupped wood, musty smell
- Sewer smell or slow drains
- New cracks or sticking doors
My tenants near Texas State say the floor by the kitchen feels warm. What should I do first?
Ask them to turn everything off and check the meter, or have a plumber do it. A warm floor that stays warm usually means a hot line leaking under the slab, so schedule detection within days.
San Marcos homes and the pipes beneath them
Across San Marcos: 1980s–2000s suburbs plus large new master-planned communities. Knowing what pipe is under your floor tells the plumber which slab leak detection method will work best.
Copper supply lines
Common in homes built from the 1960s through the early 2000s. Copper wears where it rubs against concrete or gravel, and pinhole leaks show up as homes pass 25–40 years old. Acoustic listening finds them well.
Cast-iron drains
Standard in homes built before about 1980. Cast iron rusts from the inside and cracks as the slab moves. Drain leaks never show on the water meter, so a hydrostatic test and camera inspection are used.
Polybutylene
Gray plastic pipe installed from about 1978 to 1995. It is known for failing at fittings. Tracer gas and pressure testing are often the best ways to locate leaks in it.
PEX and newer plastic
Used in most homes built since the 2000s, often run from a manifold. PEX leaks are usually at fittings or where the pipe was nicked during construction. Each run can be pressure-tested from the manifold.
Local conditions behind San Marcos slab leaks
San Marcos sits where Hill Country limestone meets Blackland clay, so ground conditions change across town. Clay areas move with drought and rain, while rockier areas make reaching a pipe harder once it leaks.
The city has a large rental market around Texas State University, older homes near downtown with original drains, and fast-growing subdivisions along I-35.
Serving homes across San Marcos, including neighborhoods near Texas State University, San Marcos River, San Marcos Premium Outlets.
Do homes on the hills west of San Marcos have more slab leak problems?
They tend to move less because they sit closer to rock, but repairs there take longer when the slab has to be opened. Pinpointing the leak keeps the opening small.
Water coming up through the floor in San Marcos?
Shut off the main water valve and call now. We’ll connect you with a licensed slab leak specialist.
Nine steps of slab leak detection in San Marcos
The same nine steps on every job, so you know what’s happening and why. Read the full process →
Listen and look first
The plumber hears what you've noticed and walks the home to look for clues.
Rule out the easy causes
Toilets, faucets, irrigation, the water heater and the AC drain are checked so you don't pay to search for the wrong leak.
Confirm the leak with the meter and a pressure test
A meter test and a pressure test prove water is escaping from the plumbing.
Isolate the leaking line
Hot, cold and branch lines are separated so the search focuses on the one that's leaking.
Test the drains, if needed
Drain leaks don't show on the meter, so they get their own hydrostatic test and camera check.
Trace the pipe's route
An electronic locator maps where the leaking line actually runs under the floor.
Pinpoint the exact spot
Acoustic listening, thermal imaging and tracer gas find where the water is escaping, and two methods must agree.
Scan the slab and mark the leak
The slab is checked for steel tendons and rebar, and the leak is marked on the floor.
Get your written report
You receive the leak's location, the line, the readings and photos in writing.
Before you book slab leak detection in San Marcos
Five minutes of setup and a two-hour wait will tell you whether your San Marcos home is losing water.
- Turn everything off. Faucets, dishwasher, washer, ice maker, sprinklers and pool fill.
- Find your meter. It is usually in a box near the street. Read the number or take a photo.
- Wait one to two hours. Use no water at all during that time.
- Read it again. If the number moved, or the small leak indicator is spinning, water is escaping.
- Narrow it down. Close the house shut-off. If the meter keeps moving, the leak is in the yard line; if it stops, it is inside, possibly under the slab.
Slab leak detection in San Marcos, done the careful way
Most of the cost of a slab leak comes from searching for it and repairing the floor afterward. Slab leak detection is all we do, so you get an exact location before anyone touches your floor.
Licensed Texas plumbers
All work is done by independent plumbers licensed in Texas who will show their license number on request.
Typical prices up front
Know the usual range before anyone arrives, and get a written quote before work starts.
Documentation you can use
Photos, readings and a written summary for your insurer or your water utility’s leak credit.
Slab leak detection prices for San Marcos homes
What most homeowners pay, and what moves the number up.
| Typical visit: $150–$600 | Can add to the price | Not part of detection |
|---|---|---|
| Meter and pressure testing | More than one leak | Foundation work |
| Electronic line tracing | A very quiet leak that needs tracer gas | Mold cleanup |
| Hot and cold line isolation | Two water heaters or a recirculation loop | Breaking or patching concrete |
| Leak marked on your floor | Lines buried under thick tile or stone | |
| Acoustic listening through the slab |
For a typical San Marcos home from Texas State University to San Marcos Premium Outlets, expect a figure in this range.
Ask for a QuoteSources: This Old House, Angi/HomeAdvisor via Bob Vila. We only do detection; you choose who does any repair.
Can I get a written report for my San Marcos rental's insurance file?
Yes. You get the leaking line, the exact location, the test readings and photos in writing, which is what insurers and water utilities usually ask for.
Why San Marcos homeowners call a slab leak detection specialist
Many general plumbers do excellent work. The difference is focus and equipment when the leak is hidden under concrete.
| What matters | Slab leak detection specialist (our network) | Typical general plumbing contractor |
|---|---|---|
| Main focus | Only finding hidden leaks under slabs | Installs, repairs and remodels across all plumbing |
| Detection tools | Acoustic ground mics, thermal imaging, tracer gas, line tracing | Varies; often a pressure test and visual inspection |
| Locating the leak | Pinpointed before any concrete is opened | May open the floor in more than one place to search |
| Drain leaks under slab | Hydrostatic, isolation test and camera find the broken section | May recommend replacing the whole drain system |
| After the leak is found | Exact spot marked and documented; you choose who fixes it | Often moves straight into its own repair or repipe |
| Paperwork | Written report with photos for insurance and water credits | Usually an invoice only |
| Typical cost to locate | $150–$600 in most San Marcos homes | Varies; exploratory openings add cost |
Tip: whoever you call, ask which detection methods they use and whether they’ll pinpoint the leak before opening the slab.
What a slab leak detection visit in San Marcos looks like
San Marcos slab leak detection follows the same careful path on every job, but the details depend on your home. A licensed plumber who serves Hays County arrives with pressure gauges, an acoustic ground microphone, a thermal camera and, when needed, tracer gas equipment.
The first hour is spent proving there is a leak and narrowing it to one line. Every fixture is turned off, the meter is watched, and the hot and cold sides are separated at the water heater. Only then does the search move to the floor.
Then comes pinpointing: the pipe is traced, the slab is checked for post-tension cables, and acoustic and thermal readings are compared until they agree. That is what makes the mark on your San Marcos floor reliable.
Before the plumber leaves, you get a written report with the leaking line, the exact location, the readings and photos. Keep it for your insurer, your water utility’s leak credit and whichever licensed plumber you choose for the repair.
If you found us by searching leak detection slab San Marcos, TX, this is the visit you can expect: careful testing first, and no concrete broken to search.
We arrange slab leak detection for homes all over San Marcos, from neighborhoods near Texas State University to those around San Marcos Premium Outlets. Most visits take two to four hours.
Questions about slab leaks in San Marcos?
Still not sure if you have a slab leak? Call and describe what you’re seeing. A licensed plumber will tell you whether it’s worth a visit.
Call (833) 841-0340Can the San Marcos River's springs raise groundwater under older homes?
Some low-lying areas near the river hold more moisture, which can leave floors damp without any leak. A meter test separates groundwater from a plumbing leak.
How do I schedule slab leak detection in a San Marcos rental between leases?
Book it for the gap between tenants, arrange access with your property manager, and ask for the written report so you can show the work to the next tenant if needed.
Do floods near the San Marcos River cause slab leaks?
Flooding doesn't usually break pipes directly, but saturated soil can shift as it dries. After water recedes, a meter test shows whether your plumbing is leaking.
Our San Marcos home has a recirculation pump. Can it hide a slab leak?
It can make one harder to notice, since hot water keeps moving through a loop that may run under the slab. Switching the pump off during testing isolates that loop.
Do San Marcos student rentals need slab leak testing between leases?
Not routinely, but checking the meter and walking the floors for warm or damp spots during turnover catches leaks before the next tenant moves in.
Can a San Marcos landlord get a leak credit after a tenant's slab leak?
Many utilities give credits to the account holder after a hidden leak is repaired. Keep the detection report and repair invoice, and ask the utility about its deadline.
When to call for slab leak detection in San Marcos
Call the same day
- Water coming up through the floor
- Sewer smell inside the home
- Meter spinning fast with everything off
- A large warm or wet area
Shut off the main water valve first.
Book this week
- Meter moves slowly with everything off
- One warm spot on the floor
- Water heater running constantly
- Bill up for a second month
Keep watching
- A single high bill with an explanation
- Hairline cracks with a normal meter test
- Slow drains in one fixture only
Repeat the meter test monthly.
Insurance and slab leaks in Texas
Coverage depends on your policy and the cause. The Texas Department of Insurance has long said the standard HO-B policy covers damage to the dwelling, including the foundation, from an accidental discharge of water from a plumbing system. Many policies still exclude wear and tear, the pipe itself, and mold.
What helps your claim: shut off the water, protect your belongings, and get the leak documented by a licensed plumber before the adjuster visits.
Ask for a leak credit
Many Texas cities and MUDs credit part of the water lost to a hidden leak once it’s repaired. Most want a paid plumber’s invoice and a request within a set number of days, and allow one credit a year.
Keep your invoice, and call your utility soon after the repair to ask about its rules and deadline.
Slab leak detection near San Marcos and across Texas
Last updated 2026-11-03