A dripping tap: which part has actually failed
Where the water comes from tells you the part. Getting that right is the difference between a five-minute job and fitting three washers into a tap that will keep dripping.
A dripping tap is worth fixing for a reason that has nothing to do with the noise: a drip runs every hour of every day, and on a hot tap you are paying to heat water that goes straight down the drain.
First: which kind of tap is it?
Almost every tap in an Australian house is one of two designs, and the repair is completely different.
- Traditional tap. The handle turns several times to open. Inside is a spindle with a rubber washer that presses onto a brass seat.
- Quarter-turn tap. The handle moves about ninety degrees, stop to stop. Inside is a ceramic disc cartridge. There is no washer.
- Mixer. One lever controlling hot and cold together, over a single cartridge.
Fitting a washer to a quarter-turn tap is impossible, and it is the most common wasted trip to the hardware shop in this whole category.
Where it drips, and what that means
| Where the water appears | Tap type | The part that has failed | Generally DIY? |
|---|---|---|---|
| Spout, tap fully closed | Traditional (multi-turn) | Washer — or the seat, if it comes back | Washer usually yes; re-seating no |
| Spout, tap fully closed | Quarter-turn or mixer | Ceramic disc cartridge | No — it is a tap component swap |
| Under the handle, while running | Either | O-ring or gland on the spindle | No |
| Base of the spout | Mixer | Body O-rings | No |
| In the cupboard below | Any | Connection, flexible hose or isolation valve — not the tap | No |
Then: where exactly is the water coming from?
Dripping from the spout, tap fully closed
Traditional tap: the washer is worn, or the seat is damaged. Quarter-turn or mixer: the cartridge.
Weeping from under the handle while the tap is running
The O-ring or gland on the spindle, not the washer. The tap shuts off properly but leaks past the stem when open.
Water appearing at the base of the spout on a mixer
The body O-rings where the spout swivels. Common on kitchen mixers that get swung side to side constantly.
Water in the cupboard underneath
Not the tap. That is a connection, a flexible hose or an isolation valve — and flexible hose failures are one of the more destructive leaks in a house, because they let go completely rather than dripping.
The one that catches people: the seat
If you replace a washer and the tap drips again within days or weeks, the seat is the problem, not the washer. The seat is the brass ring the washer closes onto. Once it is scored — by grit, or by a washer that was run hard against it after failing — every new washer gets cut by the same rough edge.
The fix is re-seating: a tool cuts the brass face flat again. Any repair that keeps failing on the same tap is telling you the seat was never addressed.
Where the line sits in Australia
If you do change a washer
The part people skip is the isolation. Turn off the water at the isolation valve for that tap, or at the main stop tap, and then open the tap to drain the line and confirm the water is genuinely off before undoing anything. A tap body opened under pressure is not a repair, it is a flood.
Take the old washer and the spindle with you to buy the replacement rather than guessing at sizes, and check the seat with a fingertip while you are in there — if it feels rough or ridged, you have found your real problem.
When to stop
Stop if the tap body turns in the bench or basin when you apply force (the whole tap is loose and this becomes a re-install), if the spindle will not come out, if there is no isolation valve and the main stop tap is seized, or if the leak turns out to be at the connection rather than the tap. All four are plumbing work, and all four get worse with persistence.
Frequently asked questions
Why does my tap still drip after changing the washer?
Almost always the seat — the brass face the washer closes onto. Once it is scored it cuts each new washer. It needs re-seating, which is a different job to a washer change.
Can I legally change a tap washer myself in Australia?
Changing a washer is generally treated as minor maintenance rather than licensed plumbing work, while replacing the tap itself is plumbing work. The exact boundary is set by each state and territory, so check your own regulator.
My mixer tap drips but there is no washer. What now?
Mixers and quarter-turn taps seal with a ceramic disc cartridge, so the repair is a cartridge replacement rather than a washer. Cartridges are model-specific, so identify the tap before buying.
Water is leaking in the cupboard under the sink, not from the tap. Is that the same fault?
No. That is a connection, a flexible hose or an isolation valve. Flexible hoses are worth taking seriously because they tend to fail suddenly rather than drip.
Sources
What this page explains is based on these official sources. If you check one and it does not match what you read here, send it to us and the article gets corrected.
- NSW Fair Trading. Plumbers, drainers and gasfitters — licensing
- Australian Building Codes Board. National Construction Code — Volume Three (Plumbing Code of Australia)