By the Peoria AZ Plumbing Co team · Published 2026-06-08 · Updated 2026-09-10
A hidden leak in a Peoria home almost always shows up as one of four things: a water bill that jumps with no change in habits, a warm patch on the floor, the sound of running water with every fixture off, or a musty smell with no visible source. If you have one of these, shut off any outdoor irrigation and test the meter with everything inside and outside closed; if the low-flow indicator still creeps after fifteen minutes, water is moving somewhere it should not be. On a slab-on-grade home, the next step is a professional acoustic locate, not opening the floor to look.
Dealing with this right now? This guide covers the background. For the actual repair, our Leak Detection page has what to expect from a visit, or call (623) 323-3182 to talk it through directly.
Why leaks hide so well in Peoria homes
Almost every home in this city sits on a concrete slab, and the supply lines that feed it run inside or under that slab. A pinhole leak there has no easy way to surface: water travels along the path of least resistance through soil and gravel before it ever shows as a wet spot, which means the damp patch on your floor is rarely directly above the actual break.
Very hard water is the other half of the story. Mineral scale thins copper pipe from the inside over years, and a line that has carried scale-heavy Central Arizona Project and groundwater supply for a couple of decades is simply more likely to pinhole than the same pipe in a soft-water city.
The meter test, done properly
Locate your water meter, usually near the curb or in a meter box in the yard. Shut off every fixture and appliance that uses water, including the irrigation timer, then watch the small triangular or dial low-flow indicator for a full fifteen minutes without touching anything. Any movement confirms a leak somewhere on your side of the meter.
Run the test twice, once with the water heater's cold supply isolated if you can, since a hot-line leak and a cold-line leak point to different parts of the house and change how a plumber approaches the locate.
What professional locating actually finds
Acoustic listening equipment picks up the specific sound water makes escaping a pressurized line, and a trained ear can walk that sound to within inches on a slab. Combined with isolating the hot and cold sides and reading pressure drop, this turns a vague "somewhere under the house" into a marked spot on the floor.
That precision is the entire point: it is the difference between opening one small section of slab and opening several in a guessing game. A locate that runs an hour can save days of unnecessary demolition.
When to act versus when to monitor
A hot-water leak is worth acting on immediately, since it wastes water you have already paid to heat and keeps your water heater cycling in a climate that already stresses it with ambient heat. A very slow cold leak with no visible damage can sometimes be scheduled rather than treated as an emergency, though it will not fix itself.
If you see any cracking in tile or flooring, or the warm spot is spreading, that is no longer a monitor situation. Call for a locate before the leak undermines the soil beneath the slab further.
The bottom line
A hidden leak rarely announces itself clearly, which is exactly why the meter test matters more than waiting for an obvious sign. Running it once after reading this is a five-minute habit that catches problems long before they become a flooring or foundation issue.
If the test comes back positive, treat locating the exact point as a separate, necessary step rather than skipping straight to opening a wall or the slab based on a guess.
What a plumber checks beyond the meter test
A professional visit typically goes further than the basic meter test: isolating the hot and cold sides separately, checking irrigation valves and hose bib connections outdoors, and inspecting any visible plumbing in a garage or utility closet for early signs of corrosion.
This broader check matters because a property can have more than one small issue at once, and treating the first leak found as the only leak sometimes means missing a second, smaller one nearby.
| Sign | Likely source |
|---|---|
| Meter moves with everything off | Active supply-line leak somewhere on your property |
| Warm spot on the floor | Hot-water line leaking under the slab |
| Musty smell, no visible water | Slow leak inside a wall or under flooring |
| Bill up, no habit change | Continuous leak, often outdoor irrigation or a slab line |
Frequently asked questions
How much water can a hidden leak actually waste?
More than most people expect. A pinhole leak running continuously for a billing cycle can add a meaningful amount to a water bill, and a hot-line leak adds a second cost in wasted energy from a water heater working to replace heated water that never reaches a fixture.
Can I find a slab leak myself?
You can confirm one exists with the meter test, but locating the exact point under a slab needs acoustic equipment and experience reading it. Guessing and opening the floor without a locate risks opening the wrong spot.
Does homeowners insurance cover a hidden leak?
Coverage varies by policy and by whether the damage is sudden versus a long-term, known leak, so check your specific policy. The pipe itself is rarely covered; the resulting water damage sometimes is.
Is a slow leak really worth fixing right away?
A slow leak under a slab can undermine the soil supporting your foundation over time and continues costing money every day it runs. It rarely gets better on its own.
Is a leak that only shows up at night significant?
Yes. A leak that seems to appear only overnight is often just easier to notice when the house is quiet and no other fixtures are running, not an indication it is any less serious than a daytime leak.
Can a leak detection company give me a warranty on the repair?
Most reputable plumbers stand behind both the locate and the repair with some form of workmanship warranty, though the length and terms vary by company. Ask specifically what is covered, the repair itself, the patch work, or both, and get the warranty terms in writing before the job starts rather than relying on a verbal assurance.
Can a smart water monitor help catch leaks earlier?
Yes, a whole-home water monitoring device can flag unusual flow patterns automatically and alert you faster than periodically checking the meter yourself, which is worth considering if you want more continuous monitoring than manual checks provide.
Reviewed by the Peoria AZ Plumbing Co team. Our work follows the International Plumbing Code (IPC) and the International Fuel Gas Code (IFGC) as adopted regionally, plus the permit and inspection requirements of the City of Peoria and Maricopa County.