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Why is my water bill so high? How to check for a hidden leak

A sudden jump in your water bill usually means a hidden leak. As of 2026, professional leak detection on the Gold Coast costs $200 to $500 or more, and a running toilet alone can waste hundreds of litres a day. Most high bills we investigate trace back to a running toilet, a hot water line leaking under the slab, or an irrigation fault.

Published 14 Aug 2026 · by
Likely causeHow to checkTypical fix cost (2026)
Running or leaking toiletFood dye in the cistern, watch the bowl$120 to $300 toilet repair
Dripping tapsLook and listen at every tap$80 to $180 plus parts
Hidden pipe leakWater meter test with everything off$200 to $500 or more to locate
Under-slab hot water leakWarm floor patch, hot system always running$1,500 to $4,000 plus to repair
Irrigation or pool faultIsolate them and re-test the meterVaries with the fault

What is the fastest way to check for a hidden leak?

The water meter test: turn off every tap, appliance and irrigation zone, then watch your meter for 10 minutes, and if the dial or numbers move, you have a leak. Your meter is at the front boundary, usually under a plastic lid near the footpath. Take a photo of the reading, wait, and compare. For slow leaks, take a reading last thing at night and again first thing in the morning before anyone uses water. Any movement with everything off is water escaping between the meter and your fixtures. This test costs nothing, takes 10 minutes, and is the first thing we would ask you to do on the phone anyway.

Could my toilet really be causing a huge bill?

Yes, a faulty toilet is the single most common cause of a mystery high bill, and a constantly running one can waste hundreds of litres a day. The frustrating part is how quiet it can be: a worn cistern outlet valve lets a thin, silent film of water run down the back of the bowl around the clock. The test is a few drops of food dye in the cistern, no flushing, wait half an hour. Colour in the bowl means the cistern is leaking through. In our experience people live with these for months because they cannot hear anything wrong. A toilet repair at $120 to $300 routinely pays for itself within a billing quarter.

What else quietly drives up a water bill?

Dripping taps, leaking hot water system relief valves, irrigation faults and pool top-up systems are the other regulars. A dripping tap wastes more than it seems, and tap repairs run $80 to $180 plus parts. Hot water systems have a relief valve that should dribble briefly during heating; one that runs constantly is both wasting water and telling you something is wrong. Irrigation systems fail invisibly, a split dripline soaking into a garden bed shows nothing on the surface. Automatic pool top-ups can mask a pool leak for a year by silently feeding it. Isolate each of these and repeat the meter test to narrow down the culprit before assuming the worst.

When does a high bill mean a serious underground leak?

If the meter runs with everything off and there is no visible cause, suspect a buried or under-slab pipe leak, especially if you also have a warm floor patch or damp ground. On the Gold Coast we see this most in homes from the 1970s through 1990s with copper hot water lines under the slab. Clues that push toward a slab leak: a warm spot on tiles, a hot water system cycling constantly, damp or lush green patches in the yard along the pipe run, and a hissing sound at fixtures with everything off. This is the point where professional leak detection at $200 to $500 or more earns its money, locating the leak precisely so the repair is one small access point rather than a search party.

Will the council give me a refund for water lost to a leak?

Many Queensland water providers offer a partial concealed-leak remission on your bill, but only if the leak was hidden, fixed promptly by a licensed plumber, and documented. On the Gold Coast, remission applications for concealed leaks generally require evidence: the plumber's invoice showing what was found and repaired, and the dates. That paperwork requirement is worth knowing before the repair, not after, because it changes what your plumber should write on the invoice. Check the current policy with the City of Gold Coast, act quickly once you know you have a leak, and keep everything. We write our leak invoices with remission applications in mind.

What should I do right now about a high bill?

Run the meter test tonight, dye-test the toilets, and call a plumber if the meter moves with everything off. That sequence sorts nearly every high-bill mystery. If the meter is still with everything off, your bill jump is usage: teenagers, guests, a new irrigation schedule, or a hot summer of pool top-ups. If the meter moves, work through toilets, taps and irrigation first because they are cheap fixes, then bring in detection gear for anything hidden. Do not wait for the next bill to confirm it. A leak that costs you one high quarter will happily cost you two.

Meter still ticking with everything off?

We find hidden leaks across the Gold Coast with pressure testing, acoustic gear and thermal imaging, and give you a fixed repair price before any work starts. Call Jieye on 0472 657 042 or book through our leak detection service page.

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