Running toilet or dripping tap: causes, fixes and when to call a plumber

24 September 2026

A toilet that keeps running is nearly always one of three faults: a worn outlet valve washer letting cistern water slip into the bowl, an inlet valve that never quite shuts off, or a float set too high so water escapes down the overflow. A dripping tap is usually a perished washer or O-ring, or a worn ceramic cartridge in a mixer. Cheap parts, all of them. The expensive bit is the water: a running toilet can waste hundreds of litres a day, and a steady drip adds thousands of litres a year to the bill.

Here’s how to work out which fault you’ve got, what’s sensible to try yourself, and where the line sits before you pick up the phone.

Why your toilet keeps running

Lift the cistern lid and watch a flush. Three checks, in order:

1. The water level. If it climbs above the overflow tube and keeps trickling, the float is set too high or the inlet valve isn’t shutting. Adjust the float down. Still creeping? The inlet valve is done.
2. The outlet valve washer. Level sitting below the overflow but water still moving into the bowl? The rubber washer at the cistern base isn’t sealing. A few drops of food dye in the cistern settles it: coloured water in the bowl without a flush means the outlet valve is leaking.
3. The button. If the flush sticks down or won’t reseat, the mechanism itself is worn out.

A float adjustment or a washer swap is genuine DIY territory for a confident householder; cisterns have an isolation tap and the parts are standard. Where it goes wrong is brittle old mechanisms that crack mid-repair, corroded connections, and concealed cisterns buried behind tiled walls, which are nobody’s Saturday project.

Can I just replace the cistern instead of the whole toilet?

Usually, yes, if the bowl is sound and a compatible cistern exists. The catches: some older designs are discontinued, a mismatched cistern can flush poorly forever, and connecting one still means working on the water supply, which in Victoria makes the installation a licensed plumber’s job. Sometimes the maths favours a whole new suite anyway, because a modern 4-star dual flush uses a fraction of the water of a 1990s unit, and that saving compounds every single day. When one of our customers had a full suite replaced recently, their review made the point we’d want made: reliable timing, “options and costs well explained,” job done efficiently. That’s how the decision should feel, whichever way it goes. And if the toilet also blocks regularly, that’s a separate fault with its own page: blocked toilet.

Fixing a dripping tap

Traditional two-handle taps drip when the jumper valve washer perishes; the fix is a new washer, sometimes with a reseat of the brass valve seat. Mixers drip when the ceramic cartridge wears; the fix is a matching cartridge. Both start with the water isolated, at the fixture’s valve or at the meter.

Two cautions, earned the hard way. Cranking a dripping tap harder to silence it chews out the washer and the seat faster, and can wreck the spindle; taps get turned off firmly, not fiercely. And if a “simple washer change” reveals a corroded spindle, a stripped thread or a seat too far gone, stop there. Forcing it is how a $20 repair becomes a full tapware replacement.

When it’s time to call

Call when the fault survives a washer or cartridge change, when the cistern is concealed, when the isolation valves are seized, which is half of older Melbourne, when the same fixture keeps failing, or when the drip comes with damp walls, floors or a water bill that’s jumped. Unexplained moisture stops being a tap problem and becomes a water leak detection job. Everything else here is bread and butter for our general plumbing crew: fixed price before we start, common parts already on the van, and one visit fixing every niggling fixture in the house for far less than three call-outs. One review put the experience simply: “He explained the problem & how he would go about fixing it. I knew the cost before he started work. But most importantly he fixed the problem.” That’s the whole job description, really.

Frequently asked questions

One running toilet wastes more water than most families drink. Call O’Shea Plumbing on 03 9888 2887 or book a repair and we’ll have it sealed, silent and off your bill.