Toilet Not Filling or Running On? Cistern Faults Explained
The common cistern faults behind slow-filling, running and weak-flushing toilets.
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Not filling
If the cistern fills slowly or not at all, the inlet valve is usually the problem. It may be blocked with grit, worn out, or the isolation tap behind the toilet may be partly closed. Check the tap first. If that is fully open, the valve likely needs cleaning or replacing.
Running constantly
A toilet that keeps running or refills on its own is usually leaking water from the cistern into the pan through a worn flush valve seal. Put a few drops of food colouring in the cistern; if colour appears in the pan without flushing, the seal is leaking. A running toilet can waste a lot of water.
Weak flush
A weak flush can be caused by a low water level in the cistern, a faulty flush valve, a partially blocked pan or, in older homes, a partial blockage in the sewer.
Buttons that stick
Push buttons can stick or fail to return. Sometimes the button linkage simply needs adjusting; other times the button assembly needs replacing.
Repair or replace?
Most cistern faults can be fixed with new parts. If the toilet is old, cracked or parts are no longer available, a new water-efficient suite may be the better option.
Ferntree Gully ground and pipes
Ferntree Gully's ground changes as you climb towards the ranges: clay and silty loam on the lower streets, rockier, steeper ground near Upper Ferntree Gully and The Basin. Most homes built before the 1980s were connected with earthenware sewer pipe, and on a slope every joint moves a little over the years and lets roots in. Water service lines from the meter are often long and run through rocky ground or under established gardens. Stormwater has to be carried down the block and away from the house. We use cameras, locators and pressure tests to see what is happening before we dig.
Related services
- Emergency plumbing
- Blocked drains
- Hot water
- Gas fitting
- Hot water replacement
- Heat pumps
- Leaking taps
- Burst pipes
- Toilets
- Leak detection
- Pipe relining
- Stormwater
- Roof and gutters
- Bathrooms
- Kitchens and laundries
- Backflow and maintenance
More guides
Questions on this topic
Why isn't my toilet filling up with water in Australia?
Most often the inlet valve is blocked or worn, or the isolation tap is partly closed. Check the tap first, then call a plumber.
What are the three common faults in a cistern toilet?
A faulty inlet valve, a leaking flush valve seal and a sticking or broken button mechanism.
Why foothills homes call us
Foothills know-how
Sloping blocks, big gums, clay sewers and gas heaters from the 1970s: this is the plumbing we work on every day.
Price first, work second
A licensed plumber finds the fault and agrees a fixed price with you before anything starts.
Camera, not guesswork
Drain cameras, pressure gauges and leak detection tools show the real cause before we dig or replace.
Respect for your home
Boot covers, drop sheets, old parts taken away and the job tested with you.
Get a free quote
Tell us what is going on and a licensed Ferntree Gully plumber will call you back.
How quoting works
Ring 03 7036 4101 or send the form with a short note, and a photo if you have one. A licensed plumber calls you back, asks a few questions and books a time. On site they find the cause, explain your options and give you a fixed price. Nothing starts until you agree, and larger jobs get a free written quote.
Need a plumber in Ferntree Gully?
Ferntree Gully, Upper Ferntree Gully, Boronia, Rowville, Knoxfield and the Knox foothills. Quote-only: the plumber finds the fault, then gives you a fixed price.