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How do I find a hidden water leak?

The short answer

Isolate the property at the meter and watch the dial. If it moves with everything off, the leak is on your side, and the meter test tells you that in fifteen minutes for free.

TradieAnswers editorial · written in-house and sourced to the authorities listed below

Checked against 4 published sources, listed in full at the end of this page. How we source this

The water meter is a measuring instrument you already own, and it will answer the main question before anyone charges you to investigate.

The meter test

  1. Turn off every tap and appliance that uses water, including ice makers and irrigation controllers.
  2. Read the meter, including the smallest dial, and write it down.
  3. Wait at least thirty minutes with nothing used.
  4. Read it again. Movement means water is passing, which means a leak on your side.
  5. To narrow it down, close the main isolation valve at the house and repeat. If the meter still moves, the leak is between the meter and the house, typically the buried service line.

Where they hide

  • Toilet outlet valves, which is the single most common answer.
  • The buried service line between the meter and the house, which often shows as an unusually green patch of lawn.
  • Irrigation solenoids that do not fully close.
  • Hot water relief valves discharging continuously, which looks like normal operation but is not.
  • Slab leaks, which sometimes show as an unexplained warm patch on a floor.

Sources

Every source below was fetched and its response recorded on the date shown. Where a government site blocks automated clients, that is noted rather than reported as a successful check.

  1. Backflow prevention · Sydney WaterChecked 2026-08-10 · responded 200 OK
  2. Water Rating (WELS) · Australian GovernmentChecked 2026-08-10 · responded 200 OK
  3. NCC 2022 Volume Three: Plumbing Code of Australia · Australian Building Codes BoardChecked 2026-08-11 · responded 200 OK
  4. Building and Plumbing Commission · Building and Plumbing Commission VictoriaChecked 2026-08-10 · live, but blocks automated clients so the specific page could not be confirmed

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