That constant sound of water running in your toilet is easy to tune out. But it’s costing you money and wasting significant water every single day. A running toilet cistern in a Melbourne home wastes between 60 and 260 litres per day depending on the fault — up to $310 per year in wasted water alone.
How to Tell If Your Cistern Is Running
If you can hear a faint hiss or trickling from the toilet when it hasn’t been flushed recently — it’s running. The dye test confirms a slow leak: put a few drops of food colouring into the cistern, wait 10 minutes without flushing. If colour appears in the bowl, water is leaking past the flapper valve.
Common Causes of a Running Cistern
Worn Flapper Valve — the most common cause. The rubber seal at the bottom of the cistern fails, allowing water to drip into the bowl. This is one of the few plumbing tasks Melbourne homeowners can legally do themselves — replacement flappers cost $10–$25 at hardware stores.
Float Level Set Too High — the float controls when the cistern stops filling. If set too high, water runs into the overflow tube continuously. Adjustable floats can be set lower — either by bending the arm on older ball-float mechanisms or adjusting the height screw on modern float valves.
Worn Fill Valve (Inlet Valve) — if the valve diaphragm is worn, it doesn’t fully close and water continues to drip in permanently. Replacing the fill valve requires turning off the supply, disconnecting the supply line, and fitting a new valve. If you’re not confident, this is a licensed plumber job — typically under 30 minutes and $150–$250 including parts.
Cracked Overflow Tube — less common. If the overflow tube is cracked, water runs continuously regardless of float position. Requires cistern disassembly — licensed plumber territory.
What a Running Cistern Costs in Melbourne
| Flow Rate | Daily Waste | Annual Cost |
|---|---|---|
| Slow trickle (~60L/day) | 60 litres | ~$72/year |
| Moderate leak (~150L/day) | 150 litres | ~$179/year |
| Fast running (~260L/day) | 260 litres | ~$310/year |
When to Call a Plumber
Call a plumber if replacing the flapper didn’t fix it, you can hear water running even when the cistern appears full, the toilet is old and parts aren’t available off the shelf, or the cistern body has visible cracks. A licensed plumber can diagnose and fix most running cistern faults in a single visit, typically $150–$300 all in.
Sedcon Plumbing fixes running toilets and cistern faults across Melbourne. Call 0468 013 012 or contact us →