Proving there's a leak
before hunting for it

The meter test

This is the foundation, and it is worth doing carefully rather than approximately.

Turn off every tap and anything that uses water automatically — the ice maker, the irrigation controller, a water softener mid-regeneration, a pool auto-fill. These are the things that produce false positives.

Find the meter, usually in a box near the street. Note the full reading, and look for the small triangular or star-shaped flow indicator — it spins if any water at all is moving. Some digital meters show a dripping-tap symbol instead.

If the flow indicator is turning with everything off, you have a leak, and you already know it is on the pressurised side. If it is still, wait an hour without using water and read the meter again. Any change is a leak too small to spin the dial visibly.

That single test distinguishes a real leak from a high bill caused by usage — and those get confused constantly, particularly during irrigation season.

Narrowing it down

Three more checks, each ruling out a large area.

Inside or outside? Most homes have a shutoff where the supply enters the house. Close it and watch the meter. Still moving means the leak is between the meter and the house — the buried service line, or irrigation. Stopped means it is inside.

Hot or cold? Shut off the cold supply valve on top of the water heater, then open a hot tap. It should stop within seconds. If water keeps running, you either have a leak on the hot side or a crossover letting cold into the hot line.

Irrigation? If there is a separate irrigation shutoff or a dedicated meter, isolate it. Irrigation leaks are common, entirely hidden, and can run for months because the system operates when nobody is watching.

Each of these takes minutes and eliminates a whole category. Doing them before calling means the visit starts from a much narrower position.

Where hidden leaks actually are

Not evenly distributed. A short list accounts for most of them.

• Toilets — the most common and the most overlooked, because a leaking flapper is silent. A few drops of food colouring in the tank, no flushing; colour in the bowl within fifteen minutes means it leaks. Do every toilet.
• Under-sink supply lines, weeping slowly inside a closed cabinet where nobody looks until the base has swollen.
• Slab leaks — hot lines first, announced by a warm patch on the floor, water audible with everything off, or a bill up 20-40%. See slab leaks.
• The irrigation system, including a valve that does not fully close and weeps between cycles.
• The water heater's T&P discharge pipe, dripping intermittently — often leaving only a white mineral crust as evidence.
• The buried service line between meter and house, which shows as a persistently green or soft patch along its route.

Signs a leak is already doing damage

The meter test finds leaks before they show. These are the ones that have been running a while.

Staining or a soft patch on a ceiling or wall, particularly a spreading ring. Paint bubbling or drywall that feels spongy. A musty smell that returns after cleaning — that is usually mould responding to moisture you cannot see.

Flooring that has cupped, lifted or gone hollow-sounding. Grout or tile coming loose in a bathroom.

Outdoors: a patch of lawn greener than everything around it, a soft area over the service line's route, or a section of ground that has visibly settled.

Any of these with a confirmed meter movement is a leak that has been running long enough to matter. The pipe repair is rarely the expensive part by that stage.

What professional detection adds

The point of proper detection is to open the smallest hole possible, in the right place, once. Guessing is what turns a leak repair into a demolition project.

Pressure isolation sections the system so the leak can be attributed to a specific run before anything is opened.

Acoustic listening picks up the specific sound pressurised water makes escaping a small opening — through concrete, through soil, through wall cavities.

Thermal imaging is effective on hot-side leaks, because a warm patch you can just about feel with a bare foot is unmistakable on camera.

Between those, a leak can usually be placed within a small area before a single tool touches the floor. That is the difference between a neat repair and a room full of exploratory holes.

Why leaks matter more here

Two local reasons, both to do with the ground.

Expansive clay swells when it takes on water and shrinks when it dries. A leak under or beside a foundation is not just wasting water — it is changing the moisture content of the soil holding the structure up, unevenly. That is what produces the cracked tile and sticking doors people notice months later and attribute to settlement.

And our hard water means the leaks that do develop often start as pinholes rather than bursts, so they run quietly for a long time before anything visible happens.

Which is the argument for the meter test as routine maintenance rather than as a response to a symptom. Ten minutes, twice a year, and it costs nothing.