What a slab leak looks like from inside the house
It rarely looks like water. That is what makes it confusing.
A warm patch of floor
The most recognisable one, and it means a hot line rather than a cold one. A section of tile that is noticeably warmer than the rest, often in a hallway or a bathroom.
Damp skirting
Wet at the bottom, dry above it. Paint bubbling along the base of a wall.
Tiles that sound hollow or start lifting
Water under the slab breaks the bond between the tile and what it was laid on.
A musty smell in one room
that does not shift.
Water pushing up at the edge of the slab,
along a path or against the outside of a wall.
A bill that has climbed
with nothing visible anywhere. High water bill
Outside, on a driveway or paving, it shows differently — a section that has started to sink, paving that has lifted at one corner, or a damp line running across concrete on a dry day.
Why Perth sand makes it worse
Under a slab on sandy ground, escaping water does not pool where it leaks. It washes fines out of the bedding sand and carries them away, then finds its way out somewhere else entirely.
Two consequences, and they both matter.
The wet patch is not the leak. Water can surface metres from where the pipe actually failed, which is exactly how people end up cutting the wrong part of a floor.
The ground under the slab moves. The fines washing away is why paving sinks and why a driveway can crack in a suburb where nothing dramatic has happened above ground. In Bull Creek, sinking paving is a reasonably reliable hint that something has been running underneath it for a while.
On top of that, the suburb's housing is largely from the 1970s, which puts a lot of buried and encased pipework at forty-five to fifty-five years old. Nothing about that is defective. It is simply old, and old pipe eventually gives up at a joint or a bend. Why hidden leaks stay hidden
How it is located
There is no instrument that sees through concrete. What there is, is a method.
Confirm the loss at the meter
With the property shut down, a moving meter proves water is escaping and suggests the size of it.
Isolate
The property is split into sections — service line, hot internal, cold internal, garden, retic — until the losing one is identified. On a suspected slab leak, separating hot from cold is particularly useful, because a warm floor has already told us which one to look at.
Pressure test
The suspect line is brought up to pressure and watched. A line that holds is ruled out. A line that bleeds down is the one.
Listen through the slab
Acoustic equipment picks up the sound of water escaping under pressure through concrete and tile. Working across the run and comparing the signal narrows it to the loudest point.
Mark it
The leak is marked on the floor or the paving as a point, not a stretch, before anything is cut.
Then you get a written price to repair it. The order matters — located, priced, repaired. Never priced against a guess about a slab nobody has tested. More on the method
Why the locating is worth more than it costs
Because concrete is the expensive part.
A slab leak marked to a point is a small cut, a repair, and a patch. The same leak treated as "somewhere under the hallway" is a floor covering removed, a series of exploratory cuts, and a reinstatement bill that dwarfs the plumbing.
The same applies outside. One lifted section of paving, or a driveway.
What we charge to come and look
Nothing. The call-out is $0, the quote is free and in writing, and there is no obligation to go ahead once you have it. Transparent pricing, no hidden costs.
Who does it
Plumbing licence 8396 and gas licence 13098, both held by Tim, who attends and does the work himself. HouseWorks Plumbing & Gas, based in Leeming, the next suburb along from Bull Creek. Monday to Friday, 7:00am to 4:00pm.
If water is actively coming up through the floor and running, that is an emergency rather than a detection job — turn it off at the meter at the front boundary if you safely can, and ring. Emergency plumbing
Get it marked before anything is cut
Tell us what you have noticed and we will call you back to arrange a time.