The average household’s leaks waste more than 9,300 gallons a year, and the ones that cost real money are the ones you can’t see. Water leak detection is the process of confirming a leak exists and pinpointing it behind drywall, under a slab, or between the meter and the house without opening anything up to look. This guide covers the signs that justify a search, the methods plumbers use in the order they use them, what leak detection services cost, and where the line falls between what you can check yourself and what needs a licensed contractor.
Key Takeaways
- A two-hour water meter test with every fixture off confirms a hidden leak before you pay anyone.
- Plumbers narrow the system down first (meter, shutoffs, visual checks), then bring in acoustic, thermal, and camera equipment.
- Leak detection cost for a slab leak runs about $150 to $400 for the search; the repair is priced separately once the leak is marked.
- In San Jose Water’s territory, every pipe on the house side of the meter is the homeowner’s to repair, including the buried line to the house.
- Water damage and freezing claims average $15,400, which is why a few hundred dollars on a search beats waiting for a wet ceiling.
- Water and gas piping on the owner’s side of the meter is C-36 plumbing contractor work under CSLB rules, so check the licence number before anyone cuts into a wall.
On This Page
- What Water Leak Detection Covers, and Where Hidden Leaks Hide in South Bay Homes
- How Do Plumbers Detect Leaks? The Methods, in the Order They’re Used
- Leak Detection Cost: What You’ll Pay to Find a Hidden Leak
- What to Check Yourself Before Booking Leak Detection Services
- Frequently Asked Questions
- Finding the Leak Is the Cheap Part
What Water Leak Detection Covers, and Where Hidden Leaks Hide in South Bay Homes
Water leak detection covers the pressurized supply side of your plumbing: the main line from the meter, the branch lines in walls and floors, and the connections to fixtures and appliances. Drain leaks are a separate search with a different tool, covered below.
The signs that usually start a search:
- A water bill that climbed with no change in how you use water
- Running water you can hear when every tap is off
- A warm patch on a slab floor
- Low pressure at one fixture, or across the whole house
- Damp drywall, swollen baseboard, or a musty smell with no visible source
Most of the housing Proper Hour Home Service works in across San Jose, Santa Clara, Los Gatos, and Fremont is 1950s to 1990s tract stock, and that age has predictable weak points. Supply lines run under the slab in a lot of it, so a pinhole shows up as a warm floor rather than a puddle. Water heater fittings and shutoff valves corrode. Toilet flappers leak silently into the bowl. And the buried line between the street meter and the house can leak into soil for months without a wet patch ever surfacing.
If you have one of those signs, run the meter test described below before you book anything.
How Do Plumbers Detect Leaks? The Methods, in the Order They’re Used
Equipment is the last step, not the first. A technician who starts with the thermal camera is guessing. Each step rules out part of the system so the expensive tools get pointed at the right place.
- Confirm it at the meter. With everything off, the meter should sit still. The EPA’s Fix a Leak Week guidance says to read it before and after a two-hour window with no water in use; any movement means a leak.
- Isolate the section. Closing the main house shutoff separates a leak in the buried service line from one indoors. Closing the water heater’s cold inlet splits hot from cold. Toilet and irrigation valves get closed one at a time.
- Check by eye and moisture meter. Under sinks, behind the water heater, at the hose bibs, at the toilet base. A pin-type moisture meter finds damp drywall that doesn’t look wet yet.
- Listen. An acoustic leak detector amplifies the hiss of water escaping a pressurized pipe. On a slab, the technician works a grid with a ground microphone and marks where the sound peaks. This finds most slab leaks.
- Image the heat. A thermal camera shows where a hot line is leaking under a floor or inside a wall. It only works on hot-side leaks, which is why it follows the isolation step.
- Camera the drain. A push camera shows cracks, offset joints, and roots in a drain or sewer lateral directly. It’s the inspection that opens every drain cleaning visit Proper Hour Home Service makes, because the camera decides whether the fix is a cable, hydro jetting, or a repair.
- Pressure test and tracer gas last. Each isolated section is pressurized and watched; a drop confirms which one is leaking. A safe tracer gas handles the line nothing else reaches.
A straightforward residential search is usually one visit. The technician should show you the mark on the floor or wall, explain why the leak is there and not somewhere else, and hand you the repair estimate before anything is opened. On Proper Hour Home Service’s plumbing services, the search uses line cameras and non-invasive methods first, and you hear the cause and the proposed fix before work starts.
Leak Detection Cost: What You’ll Pay to Find a Hidden Leak
Leak detection cost and leak repair cost are two separate numbers, and the first one is small. The search is a diagnostic fee plus the technician’s time with the equipment. The repair depends entirely on where the leak turns out to be.
| Item | Typical range | What moves the number |
|---|---|---|
| Slab leak detection (the search only) | $150 to $400, averaging about $280 | Floor area to grid, hot or cold side, access to the shutoffs |
| Pinhole leak repair in an accessible line | $150 to $800 | Pipe material, whether a wall or cabinet has to be opened |
| Rerouting a slab line overhead instead of opening the floor | $600 to $4,000 | Length of the new run, how many fixtures it feeds |
| Slab leak repair, all-in | $630 to $4,400, averaging $2,280 including detection | Cut the slab or reroute, then concrete and flooring repair after |
Those ranges are Angi’s September 2026 slab leak cost data, and they’re national figures. Water leak detection cost for your house is the estimate a technician gives after the meter test and a look at the shutoffs, not a number off a chart.
The figure that puts the search fee in perspective is what a leak costs when it isn’t found. Water damage and freezing claims averaged $15,400 across 2019 to 2023, per the Insurance Information Institute’s homeowners loss data. Most of that is drywall, flooring, and cabinets replaced after a leak ran for weeks, not the pipe.
How Proper Hour Home Service prices it: you get the estimate before the technician starts, and if the job turns out bigger once a wall or floor is open, you hear about it before anyone continues. The service call fee is waived when you go ahead with the repair. If the leak is in the buried line from the meter, the fix is water line repair and replacement, and the estimate will say whether a section repair or a full replacement is the sensible spend given the pipe’s age and material.
What to Check Yourself Before Booking Leak Detection Services
Three checks cost nothing and resolve a surprising share of hidden leaks before a technician is needed.
- The meter test. San Jose Water’s own water loss check is the local version: turn off everything inside and out, mark the sweep hand, wait 15 to 20 minutes, and see if it moved. If you then fix a leak, keep the receipt; the utility may adjust your bill.
- The toilet. A few drops of food coloring in the tank, ten minutes without flushing, then check the bowl. Color in the bowl means the flapper is leaking. It’s a ten-dollar part and a homeowner job.
- The water heater and under-sink fittings. Run a dry paper towel around every connection. Green staining on copper, corrosion crust, or a damp towel tells you where to look.
Where it stops being a homeowner job: cutting into a pressurized line, opening a slab, or touching gas. In California, water and gas piping from the owner’s side of the meter to the structure, and its maintenance, falls under the C-36 plumbing contractor classification set by the Contractors State License Board, and you can look any number up on the CSLB site before you book. Proper Hour Home Service is a licensed contractor, CSLB #1131330, and the number is on every page of the site for that reason.
If the meter test points at the buried service line and you’re in Fremont, which is Alameda County rather than Santa Clara, the page on water line repair for Centerville homeowners in Fremont covers the repair-or-replace decision for that line.
Frequently Asked Questions
How much does leak detection cost in San Jose?
Finding a slab leak costs around $150 to $400 for the search itself, averaging about $280 in Angi’s September 2026 national data. That fee covers the technician’s time with acoustic, thermal, and camera equipment and ends with the leak marked and a repair estimate in hand. The repair is priced separately.
Proper Hour Home Service gives you the estimate before work starts and waives the service call fee when you approve the repair.
What do plumbers use to detect water leaks?
Plumbers use the water meter and shutoff valves first to confirm the leak and narrow it to one section. Then come a moisture meter for walls, an acoustic listening device for pressurized lines and slabs, a thermal camera for hot-side leaks, and a push camera for drains. Pressure testing and tracer gas handle whatever is left.
The order matters more than the equipment. Isolation first, then instruments.
How long does it take a plumber to find a leak?
Most residential leak searches finish in one visit, usually an hour or two when the shutoffs are accessible and the meter reading is clear. A slab leak that needs the whole floor gridded with a ground microphone takes longer. Proper Hour Home Service books seven days a week, 8am to 8pm, with same-day visits when a slot is open.
If the technician can’t show you a marked location and explain why the leak is there, the search isn’t finished.
Is the leak my responsibility or the water company’s?
In San Jose Water’s service area, the customer is responsible for every pipe on the house side of the meter, including the buried line from the meter to the home. The utility maintains the meter and the street side. If the meter still moves with the house shutoff closed, the leak is in that buried line and it’s yours.
Keep repair receipts. San Jose Water may adjust the bill for water lost to a leak you’ve fixed.
Do I need a licensed contractor to fix a water leak in California?
Replacing a toilet flapper or a supply-line fitting under a sink is homeowner work. Cutting into pressurized copper or PEX, rerouting a slab line, replacing the buried service line, or touching gas piping is C-36 plumbing contractor work under CSLB classifications, and whoever does it should hold a California licence you can verify. Proper Hour Home Service is a licensed contractor, CSLB #1131330.
Ask for the number before anyone opens a wall. A legitimate contractor expects the question.
Finding the Leak Is the Cheap Part
If the meter moved during the test, you have a leak, and the only decision is how soon to locate it. The search is a few hundred dollars. The repair is a few hundred to a few thousand depending on where the leak is. The damage from waiting is usually more than both. Schedule a leak detection visit with Proper Hour Home Service, or call the number at the top of the page, and the technician will tell you where the leak is and what the fix costs before anything is opened.
