Why Your Toilet Keeps Running
Water that will not stop after a flush has three usual sources, and all of them sit inside the cistern. When a toilet keeps running, the fault is a valve, a seal or the float setting behind it. Lawnton Plumbing Services wrote this guide so you can name the part, run one simple check, and hand the rest to a licensed plumber.
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The Three Causes of a Running Toilet
Three causes sit behind almost every running toilet: an inlet valve that will not shut off, a flush valve seal worn enough to leak into the pan, and a water level set so high it runs out through the overflow.
Each fault leaves its own sign.
Inlet valve
this part refills the cistern after each flush and closes once the float hits its set level. A valve that stays open keeps filling, and a hissing or trickling sound after the refill finishes points straight at it.
Flush valve seal
this seal holds the stored water between flushes. Wear lets the water slip down into the pan, so the inlet valve keeps topping up every few minutes with nobody pressing the button.
Overflow
this outlet carries spare water away instead of letting it flood the floor. Water flowing from it, including a drip pipe outside, means the level sits past its mark, so the valve or float needs attention.
The float links the first and third causes. Set it too high and the water climbs to the overflow even with a healthy valve.
Slow, Partial or No Refill After a Flush
A slow or empty refill usually traces to a worn or partly blocked inlet valve, a float sitting too low, or a stop tap that has not been opened all the way. The stop tap is the easy one to rule out, because a handle a quarter-turn short of open leaves the flow feeble.
Sneakier still is water running while the level never climbs. There the flush valve seal can be letting water out at the same rate it comes in, so no amount of filling brings the cistern up. The colour check below settles which fault you have.
Which Cistern Parts a Home Owner May Replace
The QBCC names three cistern parts as unregulated work that anyone who has the knowledge and skill may repair or replace. Those parts are the drop valve washer, the float valve washer and the suction cup rubber. No licence, approval or report is needed, though the finished job still has to meet the standards.
Every other toilet repair is minor work for a QBCC licensee: no permit and no Form 4, but the licence is not optional.
Rentals run on their own line. Queensland tenancy law has the owner or manager keep a rental in good repair, and tenants must pass faults on as soon as they notice them.
Check for a Silent Leak With Food Colouring
Run the test like this:
- Squeeze several drops of food colouring into the cistern water.
- Leave the toilet alone, with no flush.
- Check the bowl: colour there means water is escaping past the seal and down into the pan.
- Flush afterwards, since the dye will not mark a ceramic bowl.
No colour in the bowl? The flush valve is holding, so look next at the inlet valve and the level setting.
No dye in the house? Press a strip of dry toilet paper flat against the back of the bowl, above the water line. Dry paper means no trickle; damp paper means a leak.
What a Running Cistern Does to Your Water Bill
No, Unitywater's concealed leak adjustment does not apply to water lost through a leaking cistern. The policy covers hidden pipe breaks only, and it rules out cisterns, taps, hot water systems and other water appliances.
The property owner carries primary responsibility for leaks and losses on the property. That lands hard on landlords whose tenants pay the usage account, because a worn seal quietly bleeds that bill upward week after week.
For a tenancy, a running cistern counts as a routine repair. Queensland's emergency list names a blocked or broken toilet, not one that keeps going, so the fix happens within a reasonable time after the tenant tells the owner or manager.
When to Call a Plumber
Ring once the colour shows up, or once the hiss outlasts your patience with the float arm. Our toilet repairs page covers the valves, seals and pan connectors on suites across the suburb.
Cistern age matters more than house age here. Housing spread from the 1960s onward, so plenty of bathrooms still run originals inside the cistern, and the springs and rubbers from that era have had decades of humid subtropical air to soften them.
Toilet and Cistern Questions
Call (07) 3524 0766Why does my toilet keep running after I flush?
Usually one of three parts. The inlet valve may not be shutting off, the flush valve seal can be worn and leaking water into the pan, or the water sits so high it escapes down the overflow. A hissing sound that never quits points to the inlet valve; a cistern that tops itself up points to the seal.
Why is my toilet cistern not filling up?
A worn or partly blocked inlet valve, a float sitting too low, or a stop tap that has not been opened all the way are the usual reasons. Water running with the level stuck low points to a leaking flush valve seal instead. A licensed plumber sorts any of them.
How do I check my cistern for a silent leak?
Squeeze several drops of food colouring into the cistern, then wait without flushing. Colour drifting into the bowl means a leak past the seal; flush afterwards, since the dye will not mark a ceramic bowl. Unitywater recommends the same check for households.
What is the overflow in a toilet cistern?
An overflow is the spare outlet built into every cistern, carrying excess water down into the pan instead of onto your floor. When the inlet valve will not close or the float rides too high, water reaches it and runs out. Unitywater charges for every litre that passes through.
Ring Us About the Running CisternWe'll call you back.
Phone (07) 3524 0766 for a licensed plumber in Lawnton. We work under QBCC No: 15024607, with flat-rate pricing, no hidden fees and same-day where we can.
To claim your $0 call-out fee, call (07) 3524 0766 today.