A dripping tap is one of the most common plumbing complaints, and changing the washer is a job many homeowners feel confident tackling. Done correctly, it's a straightforward repair. But a surprising number of "replaced washers" don't fix the drip, because the washer isn't always the actual cause.
Before you start
You'll need an adjustable spanner, a screwdriver, a new washer of the correct size, and ideally a new O-ring and jumper valve. Most importantly, you need to isolate the water supply to that tap. If there's an isolation valve under the sink, turn that off; otherwise turn off the main water supply to the house.
Open the tap fully after isolating to release any pressure and confirm the water is off. If water keeps flowing, the isolation isn't working — stop and fix that first. A seized main valve is a common problem; see our advice in common DIY plumbing mistakes
Step-by-step: changing a tap washer
- Isolate the water and open the tap to release pressure.
- Remove the tap handle — usually a decorative cap hides the retaining screw. Remove the screw and lift off the handle.
- Unscrew the tap bonnet using the spanner. Turn anticlockwise; protect the basin with a cloth to avoid scratching.
- Lift out the tap body and locate the washer at the base. The washer sits on the jumper valve, which presses against the seat.
- Replace the washer (and the O-ring if present). Note the size and type — common sizes are 12mm and 15mm, and there are flat and domed varieties.
- Reassemble in reverse order, hand-tightening the bonnet then a quarter-turn with the spanner. Don't overtighten.
- Turn the water back on and test. Check for leaks around the bonnet while the tap is closed and open.
When a new washer won't fix the drip
If you've replaced the washer and the tap still drips, the most likely cause is a worn or grooved seat — the brass surface the washer presses against. Over time, water and grit cut channels into the seat so that no washer can seal against it. The fix is to re-seat (machine the surface smooth) or replace the entire tap assembly.
Other signs a washer alone won't solve the problem:
- The tap drips from around the spindle when open, not from the spout — this is a worn O-ring.
- The tap is stiff or hard to turn — the bonnet may be corroded or the jumper valve seized.
- The tap body is cracked or corroded — replacement is the only reliable option.
When to call a plumber
If the tap still drips after a washer replacement, the seat needs re-seating or the tap needs replacing. If the bonnet is seized and won't unscrew, forcing it risks cracking the basin or the pipework behind the wall. And if you're not confident isolating the water or the main valve doesn't work, call a plumber rather than risk a flood.
Our general plumbing services cover tap repairs and replacements across the Gold Coast, including re-seating and full tap upgrades.
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