Two valves control your cistern, and one of them has failed
Every cistern has an inlet side and an outlet side. The fill valve, controlled by a float, lets water in until the set level is reached and then shuts. The outlet valve opens when you press the button and seals against a rubber washer when the flush finishes. A toilet that keeps running has a fault in one of those two. If water is trickling into the bowl constantly, the outlet washer is not sealing, which is far and away the most common failure because the rubber hardens, distorts or collects grit with age. If you can hear the cistern hissing or refilling in short bursts, the fill valve is not shutting off cleanly, and the excess is escaping down the overflow into the bowl. Either way the water goes the same place, which is why the two faults look identical from the bathroom doorway.
The ten-minute checks worth doing yourself
Take the cistern lid off and look. If the water level is sitting at or above the top of the overflow tube, the fill valve is overfilling and the excess is running to the bowl. If the level is normal but the bowl still trickles, the outlet washer is leaking past. A drop of food dye in the cistern confirms it: do not flush, wait 15 minutes, and coloured water in the bowl means the outlet seal is passing. Also check the button has not jammed and the flush cable or linkage is not held slightly open, which happens more than you would think on aged dual-flush buttons. None of this needs tools, and all of it makes your description on the phone more useful.
What the fault costs to fix on the Gold Coast
| Fault | The fix | Typical Gold Coast cost as of 2026 |
|---|---|---|
| Outlet valve washer worn, bowl trickles constantly | Replace washer or outlet valve | $120 to $300 |
| Fill valve not shutting off, cistern hisses | Replace fill valve | $120 to $300 |
| Button or linkage jamming | Adjust or replace mechanism | $120 to $300 |
| Cistern cracked or leaking externally | Replace the suite | $350 to $750 installation plus the suite |
| Discontinued cistern with no parts available | Replace the suite | $350 to $750 installation plus the suite |
Most repairs land in a single visit because we carry the common valve and washer stock for the cisterns Gold Coast homes actually have. Where a cistern is obsolete and parts are genuinely unobtainable, we say so and quote the suite replacement rather than botching an adaptor fix that will leak again.
A running toilet is quietly one of the most expensive faults in the house
The trickle looks trivial, but it runs 24 hours a day. A slow leak past the outlet washer wastes tens of litres a day, and a failed valve running steadily can push past several hundred litres a day, every day, until it is fixed. On a metered Gold Coast water bill that shows up as a jump you notice the following quarter, and it is the single most common answer when a customer asks us why their bill spiked with no visible leak anywhere. If you are chasing an unexplained bill increase, the dye test above is the first thing to do, and your water meter is the second: with every tap off, a meter that keeps ticking over means water is moving somewhere.
When it is urgent and when it can wait
A running toilet is rarely a flooding risk, because everything is going into the bowl and away down the drain. It can usually wait a few days for a business-hours visit, and we will tell you that on the phone rather than sell you an emergency callout. The exceptions: water escaping from the cistern onto the floor rather than into the bowl, a property on a concealed-leak dispute where metered usage matters, or a toilet that is both running and gurgling, which points at a drainage problem as well. Renters in Queensland should report it to the property manager promptly, since a running toilet from fair wear and tear is generally a repair the lessor is responsible for arranging, and delay only inflates the water charges argument later.
Stop paying for water you never use. Call Hills Plumbing & Gas on 0472 657 042 for a fixed-price toilet repair, usually done in one visit, or book through our leaking taps and toilets service page. QBCC licence 15243081.
Sources: Residential Tenancies and Rooming Accommodation Act 2008 (Qld) for rental repair responsibilities; WELS scheme information on fixture water use. Check current rules for your tenancy situation.