Traced with equipment before anything is opened, including under a slab, where the fault frequently announces itself as a warm patch on the floor.
Online Now!·--:--
Most hidden leaks are unhelpful. They surface somewhere other than where they started, or they never surface at all and the only clue is a bill. There is one exception, and on slab-on-ground housing it is worth knowing about.
If a hot water line running within or beneath the slab starts leaking, the water is heated and the concrete conducts. The warmth reaches the surface, and you get a patch of floor that is noticeably warmer than the rest. Bare feet in the morning is how most people find it.
That is unusually generous, because it points at the location rather than merely announcing that something is wrong. The supporting signs are worth knowing too: a sound of running water with every tap closed, a hot water system cycling more than it used to, and a bill that has risen with nothing visibly wet anywhere.
None of that means concrete has to come up. It means it gets located precisely first, with acoustic listening, pressure testing on the hot and cold lines separately, and thermal imaging. Only then is it worth discussing whether the answer is opening one small area or abandoning that run and re-routing it.
Do not wait for it to get wet. That is the most useful symptom a hidden leak ever gives you, and it is worth acting on while it is still just warm.
A leaking hot water line under concrete warms the floor above it. Concrete moves heat well and spreads it, so what you feel is a warm patch or a warm strip rather than a hot spot.
On slab-on-ground housing, which is most of this suburb, that is the clearest single symptom of a leak you will get. It is also the one people most often dismiss as sun through a window.
The test is simple. Check it early in the morning before the sun has been on the floor, and check it in a room the sun does not reach. If the patch is still warm, it is not the sun.
A faint sound of moving water when nothing is on is a real symptom rather than imagination. Stand still in a quiet house at night, with the fridge and the air conditioning off, and listen near the floor.
A pressurised leak makes noise continuously because the mains keeps feeding it. That is the difference between a leak and a drain, which only makes noise when something is running.
If you can hear it, note roughly where. Acoustic equipment does the same job far better, but knowing which half of the house to start in saves time.
Hot water being lost is hot water being reheated. A unit that fires more often than it used to, for a household that has not changed its habits, is heating water that is going somewhere other than a tap.
It frequently shows on the energy bill before it shows anywhere else, and it is easy to attribute to a colder month or a higher tariff.
Read it alongside the warm patch and the sound. Any one of the three on its own is worth a look. Two together is a hot water line under the slab.
Close everything, including the machine and the dishwasher, and watch the smallest dial on the meter for two minutes. If it moves, water is genuinely leaving the property.
Then close the valve on the inlet to the hot water unit and watch again. Still moving means the leak is on the cold side. Stopped means it is the unit or the hot line past it, which is the slab case.
Two minutes of that halves the search area before anybody arrives, and it is the single most useful thing a householder can do.
Not the first one, and never before the leak has been located precisely. Cutting concrete in an occupied house is dust, noise and a floor covering that does not go back the way it came.
Which is exactly why locating properly is worth paying for. Acoustic listening, thermal imaging and pressure testing between them get most slab leaks down to a small area before anything is cut.
There is frequently an alternative worth pricing. Re-routing the affected line overhead or around the outside of the building avoids the slab altogether, and on some houses it is both cheaper and less disruptive than going through it.
Water follows the underside of a slab, the line of a pipe trench or the back of a wall, and it surfaces wherever it finally finds a way out. A damp patch at a skirting can be metres from the failure.
So the wet spot is a clue rather than an address. Opening it is quick, satisfying and quite often reveals nothing but wet.
That is the argument for locating before cutting, and it applies just as much on a slab as it does in a wall.
The connectors feeding taps and cisterns sit at full mains pressure permanently, inside cupboards, and they are rated for about five years.
When one fails it does so completely and immediately. There is no leak that grows, which is why the first anybody knows is usually a ceiling.
Replacing them all together is the sensible version, because they went in on the same day and they will reach the end at roughly the same time.
This is how most slab leaks announce themselves, because there is nothing to see. The water goes into the ground under the house and the only evidence is the quarterly account.
Start with the meter test, because it splits the problem in two at no cost. A moving dial is a leak to find. A still dial with a high bill is usually irrigation, a pool topping itself up, or a cistern passing quietly.
If it is a leak, the order of work is meter, then the hot water isolation, then the service line from the meter to the house. That last one is the expensive possibility and the one worth ruling out early.
What a burst costs is decided in the minutes between the failure and somebody closing the water. The repair afterwards is ordinary work. The minutes before it are flooring, cabinetry and ceilings.
Find the meter and its tap on a dry afternoon and check it actually turns. On properties of this age they seize, and eleven at night is the worst possible moment to discover that.
Learn the isolating valves inside too: under the sink, behind the toilet, at the hot water unit. Closing one of those stops a specific problem without taking water off the whole house.
Acoustic listening picks up the noise a pressurised leak makes through concrete and soil. On a slab that is the primary tool, because the slab that hides the pipe also carries the sound.
Thermal imaging finds the temperature difference a hot water leak leaves in the floor above it, which is the instrument version of the warm patch you can feel with a hand.
Pressure testing isolates sections until the one losing water gives itself away. Between the three, most slab leaks get located to within a small area before anything is cut.
The domestic ceiling is 500 kPa static at any outlet, and the valve that holds it there wears out at somewhere around eight to twelve years. It fails open, so nothing warns you.
Read the symptoms together rather than separately. Taps that keep dripping after being repaired, water hammer that was not there before, and appliance inlet valves failing early all point the same way.
It matters more under a slab than anywhere else, because higher pressure means a leak in a buried line loses more water and does it faster. Measuring takes a gauge and two minutes.
Fixed price agreed before anything starts. These are indicative 2026 ranges.
Water stopped and the situation stabilised, at any hour.
Acoustic, pressure and thermal, with nothing cut into concrete to find it.
The same approach, for a leak that is not under the slab.
Depending on the pipe, the material and how it has to be reached.
Where abandoning the line under the slab is the better answer than opening it.
Whether the house is on a slab and whether any part of the floor is warm. Those two answers narrow it enormously before anybody arrives.
Acoustic listening, pressure testing on hot and cold separately, and thermal imaging over the suspect area.
Open one small area, or abandon the run and re-route it. Both get priced so you are choosing rather than being told.
What failed, where, and what it took, at the figure agreed before we started.
Shut it off at the meter and ring. A licensed plumber can be heading toward you while you are still on the call.
Call 1300 381 569What Seven Hills locals ask us before booking a plumber.
Ask us yours
On a house built on a concrete slab, that is one of the clearest signs there is of a leaking hot water line running within or beneath the slab. The water is heated, the slab conducts, and the warmth reaches the surface above the leak. It is one of the few plumbing faults that genuinely tells you where it is.
A sound of running water when every tap is closed. A hot water system that cycles more than it used to. A water bill that has climbed with nothing visibly wet. And in some cases a damp patch appearing at the edge of the floor where the slab meets a wall.
Not necessarily, and not until it has been located precisely. Depending on where the line runs and what it serves, the options can include locating and opening one small area, or abandoning the affected run and re-routing it above ground or through the roof space. We would rather set both out than assume.
Acoustic listening, pressure testing on the isolated hot and cold lines separately, and thermal imaging, which on a warm slab leak is particularly effective. The point of all of it is to be certain before any concrete is touched.
Turn the water off at the meter before anything else, then ring. How much a burst costs is largely decided by how long the supply stayed on.
Yes. Close every tap and appliance and watch the smallest dial on the meter. If it creeps, water is genuinely leaving somewhere on your side, and under a slab it can do that for a long time without ever showing at the surface.
Locating a slab leak is $350 to $700. Locating a concealed leak generally is $250 to $600. A burst repair is $300 to $900. Re-routing an affected run is quoted once it is located.
Tell us whether the house is on a slab and whether any part of the floor feels warm. If the answer to the second is yes, that is most of the diagnosis already done.
Located with equipment, opened only where it must be, and re-routed where that is better.
Online Now!·--:--
