Warm patch on the tile. A meter that will not stop. A bill that jumped for no reason. Before anyone opens concrete, the line has to be found, precisely, and without breaking anything to do it.
Non-destructive locating. Nothing is cut until you know exactly where and why.
Arizona homes are built slab-on-grade, overwhelmingly. Concrete poured directly on prepared ground, no basement, no crawlspace to speak of in most of the housing stock. It is the right way to build here and it works well. It also means that a large share of the pressurized water lines in the average Arizona house run through, under, or embedded in that concrete.
In a house with a basement, a failed supply line makes a puddle somewhere a person can walk to. Under a slab, the same failure has nowhere to present itself. The water goes into the ground under the concrete, or it tracks along the line until it finds an edge, or it heats a patch of floor from below. You get symptoms rather than evidence.
Add the local water. Arizona carries one of the heaviest mineral loads in the country, and hot mineral-rich water moving through copper under thermal stress is a combination that shortens the life of the pipe. Add caliche in the soil, which means the ground under the slab does not always behave like soft earth. The result is a failure mode that dominates conversation among plumbers in Phoenix and Tucson and barely registers in Minneapolis.
Locating is a distinct trade skill. It is not "look for the wet bit", and it is not something to guess at when the wrong guess costs a hole in your floor.
The strongest single indicator there is, and effectively specific to the hot water line. Walk the house barefoot in the morning before the sun has been on the floor. A patch that is consistently warmer than the tile a foot away, in a place with no sunlight and no heated run beneath it, is a hot line losing water under the concrete.
Nearly as strong, and it covers both hot and cold. If the low-flow indicator turns while the house is shut down, water is leaving the system. It does not by itself prove the leak is under the slab, but combined with symptom one it very nearly does.
Useful as a trigger rather than a diagnosis. Arizona bills climb in summer for legitimate reasons, so a July increase means less than a February one. What matters is a jump with no change in occupancy, irrigation or season.
Late at night, with the air conditioning cycled off, put an ear near the floor in different rooms. A faint continuous hiss or rush with no fixture running is real evidence. This is the same physical signal the acoustic equipment amplifies, just at the limit of human hearing.
Slower, later and more serious. Prolonged saturation changes the ground the slab bears on. New cracking in tile grout, a door that has started to bind, or a hairline crack in drywall that keeps growing all belong on the list.
Water tracking along the line until it finds an edge shows up as damp baseboard, lifting flooring at a threshold, a musty smell in a closet on an exterior wall, or a persistently damp patch on a patio or driveway with no sprinkler near it.
Warm floor, moving meter, unexplained bill. Any two of those together justify a locate. All three together and it is very likely a slab leak on the hot side.
This is worth doing before you call, because it turns "something feels wrong" into a measurement.
Shut down every water use in the house. Taps, showers, toilets left alone, dishwasher, washing machine. Then the ones people forget: the ice maker, the irrigation controller (set it to off, not just between cycles), the pool auto-fill, an evaporative cooler if you run one, a water softener mid-regeneration, and a reverse osmosis unit that may be filling its tank.
Open the meter box at the street. Look before you put a hand in it, scorpions and spiders shelter in these boxes in this state. Find the low-flow indicator, which is a small triangle, star or freely spinning dial designed to register tiny flows. Watch it for two minutes.
If it is turning, note the meter reading, wait fifteen minutes without using any water, and read it again. The difference is your leak rate, and it is genuinely useful information for the plumber. If it does not move at all, your problem is on the drain side, or intermittent, or not a leak, and that is worth knowing too.
Tell us the reading and the interval and we will tell you what it suggests.
That plus a moving meter is the classic pair. Call and describe it.
Hot water is chemically more aggressive than cold. It also expands the pipe. A copper line under a slab is constrained, it cannot move freely as it heats and cools, so instead it works against whatever surrounds it: concrete, sand bedding, caliche, a sleeve that has degraded. Decades of that cycling abrades the wall of the pipe from the outside while hot mineral-heavy water works on it from the inside.
The failure is usually a pinhole rather than a split, which is why the symptoms are subtle and why the leak can run for a long time before anyone notices. It is also why a warm floor is such a giveaway: the escaping water is hot, and concrete conducts heat well enough to bring that to the surface.
Cold-side slab leaks happen too, and they are harder. No thermal signature, no warm floor, and often no sound if the pressure loss is small. Those are found by isolation and by meter behavior rather than by walking around barefoot.
Slab leak repair, what happens once it is found.
Pipe rerouting, the alternative to opening concrete.
Leak detection, when it turns out not to be the slab.
Water escaping a pressurized line makes a specific sound as it forces through a small opening. Ground microphones and amplified listening discs pick that up through concrete and let the plumber walk the signal to its loudest point.
The system is split into sections at manifolds, stops and the softener loop, and each is pressurized and watched independently. This narrows the leak to a branch before any locating instrument comes out, and it is what separates a two-hour job from a six-hour one.
An infrared camera maps surface temperature across the floor. A hot line losing water leaves a plume that reads clearly on tile and concrete. Less useful over thick carpet, wood or a slab with radiant runs already in it.
The suspect line is drained and charged with an inert helium and nitrogen mix. The gas escapes at the fault, migrates up through the slab and is detected at the surface with a probe. This is the method that works when the leak is too small or too intermittent to hear.
In practice a plumber uses two or three of these together and cross-checks. Agreement between an acoustic peak, a thermal plume and an isolation result is what produces a mark on the floor you can trust enough to cut next to.
A great deal of Arizona housing built from the 1990s onward, and most of the master-planned growth in the East Valley, the Pinal corridor and the West Valley, sits on post-tension slabs. Steel tendons run through the concrete under very high tension. Cutting one is genuinely hazardous and structurally significant, and it is not a mistake anyone gets to make twice.
On these houses, precision in the locate is not a nicety. Either the opening has to be planned around a known tendon layout, or the sensible answer is to abandon the under-slab line entirely and run a new one overhead. That decision belongs on the rerouting page, but it starts here, with a locate accurate enough to make the choice properly.
It tells you where. It does not tell you why, and it does not tell you whether the rest of the line is in similar condition. If a house has had two prior slab leaks on the same system, a third locate is really a conversation about the whole run, not one spot.
It also does not decide the repair for you. Spot repair, reroute or partial repipe is a separate judgement involving pipe material, age, leak history, flooring, slab type and how long you plan to stay in the house.
We will explain what the visit covers before you book it.
Detection is priced on its own, and there is a good reason for that beyond bookkeeping. A meaningful share of locates end with "there is no slab leak here", the water is going to irrigation, a pool line, the service line from the meter, a silently cycling toilet, or a softener stuck in regeneration. If locating were folded into the repair price, there would be a quiet commercial reason to find a leak under every slab. Keeping it separate removes that.
It also gives you something useful to hold: a marked location, an approximate depth, a run direction and a plumber's assessment. With that in hand you can make the repair decision deliberately, get a second opinion on the approach if you want one, and understand what you are agreeing to before concrete gets cut.
As with everything else on this site, we do not publish figures. The plumber gives you the number on site, before starting, and you approve it.
The combination is what tells you. One symptom alone is weak evidence; three together is close to conclusive. A warm or hot patch on the floor, a water meter that keeps moving with every fixture in the house closed, and a usage bill that jumped without a change in habits, that trio points at a pressurized line under the concrete almost every time.
Individually, a warm floor can be a sun patch or a heated line running where it should, and a high bill can be irrigation. That is exactly why locating comes before repairing.
Yes, and it is worth ten minutes. Turn off every fixture and appliance that uses water, including ice makers, irrigation controllers, evaporative coolers and pool auto-fill. Then open the meter box and watch the low-flow indicator, usually a small triangle, star or dial that spins on very low volumes.
If it moves at all, water is leaving the system somewhere. Note the reading, wait fifteen minutes, read it again. That gives a plumber a real number to work from. If it does not move at all, your leak is on the drain side or is not a leak.
Hot water is more aggressive chemically, it moves more, and it expands and contracts through a wider range. Under a slab, a copper line encased in or resting on concrete cannot move freely, so thermal cycling grinds it against the surrounding material year after year. Combine that abrasion with hot, mineral-heavy Arizona water and the hot side statistically goes first.
This is why a warm spot is such a strong indicator, and why a slab leak on the cold side is usually found by the meter rather than by the floor.
Four techniques, usually in combination. Acoustic listening amplifies the sound of water escaping under pressure through concrete. Pressure isolation splits the system into sections so the leak can be narrowed to a zone. Thermal imaging maps temperature across the floor to find the plume from a hot line. Tracer gas, an inert helium and nitrogen mix introduced into a drained line, surfaces through the slab and is picked up by a probe.
No single method is right for every house. Tile over a thick slab behaves differently from polished concrete, and a house with a softener loop and multiple manifolds isolates differently from a simple two-branch layout.
Proper detection is non-destructive. Nothing is cut, drilled or opened during the locating stage. That is the entire point of doing it: you are buying certainty about where to open the floor so that exactly one hole gets made instead of three.
Occasionally a plumber will need to remove an access panel or pull a toilet to reach a manifold for isolation. That is reversible and you will be told before it happens.
Because they are genuinely different pieces of work with different skills and equipment behind them, and because a fair number of detection jobs end with the conclusion that there is no slab leak at all. If detection were bundled into repair, there would be a quiet incentive to find one.
Paying for the locate and then deciding on the repair separately also means you can take the location report and think about your options, which on a slab is a decision worth thinking about.
Significantly, and it is one of the most important things to establish early. Post-tension slabs, common across newer master-planned subdivisions in the East Valley, the Pinal corridor and the West Valley growth areas, have steel tendons under high tension running through the concrete. Cutting one is dangerous and structurally serious.
Detection on a post-tension slab has to be precise enough that any subsequent opening can be planned around the tendon layout, and it is one of the strongest arguments for rerouting the line overhead instead of opening the floor at all.
Most locates are a single visit of one to three hours. Complex houses take longer: large square footage, multiple manifolds, additions built at different times, or a slab with unusual flooring over it. Houses where the leak is intermittent are the hardest, because the plumber has to catch it while it is running.
You will normally know the location and the approximate depth before the plumber leaves.
That happens, and it is a good outcome. Very often the culprit is irrigation, a pool line, the service line between the meter and the house, a toilet fill valve cycling silently, or a water softener stuck in regeneration. All of those produce a moving meter and an ugly bill without a single drop under the concrete.
A proper locate rules the slab in or out and then points at the real source. The broader hunt is covered on the leak detection page.
It is not a same-hour emergency in most cases, because the water usually is not surfacing on your flooring. It is also not something to sit on. A pressurized line under a slab runs continuously, it does not pause overnight, so the water lost and the bill both accumulate steadily, and prolonged saturation under a slab is not good for the ground the slab rests on.
Reasonable timescale: get it located this week, decide on the repair with the location in hand.
Where the method allows it, yes. Position gets marked on the floor; approximate depth and the run direction matter for planning the repair, because a line eight inches down under tile is a different job from one at the base of a thick slab under a load-bearing wall.
That information is also what makes the reroute-versus-open decision an informed one rather than a preference.
Get it located before anyone talks to you about opening concrete. One call, a marked spot on the floor, and a decision you can actually make.
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