How to Replace a Tap Washer (Step-by-Step Guide for Australian Homes)

How to Replace a Tap Washer (Step-by-Step Guide for Australian Homes) — a Prime Plumbing & Gasfitting plain-English guide to tap washer replacement for Melbourne homeowners. Below we cover what works, what doesn't, and when to call a licensed plumber.

Tap washer replacement is the cheapest, fastest fix for a dripping compression tap — and one of the few plumbing jobs Victorian homeowners can legally do themselves on their own home. This guide walks you through the full tap washer replacement process step by step, the tools you need, and the signs that mean the job has grown past a simple washer swap.

Quick answer: Tap washer replacement is a 15-30 minute job on a compression tap (the older style with two separate hot + cold handles, each turning multiple full rotations). You need an adjustable shifter, a Phillips screwdriver, a small assorted-size washer pack (around $8 at Bunnings), and access to the supply isolation valve. Stop before you start if: your tap has a single handle that lifts up and rotates (that's a mixer — needs a cartridge replacement, not a washer), the leak is at the base of the tap rather than the spout (different fix), you can't shut the water off cleanly, or the tap body is corroded inside when you open it. The full step-by-step is below.

A new tap washer only fixes one type of tap: the compression tap. Identify yours before you start:

• Compression tap — two separate handles (hot + cold), each turning multiple full rotations. Needs a washer replacement (this guide).
• Mixer tap — single handle that lifts up and rotates left/right. Needs a cartridge replacement (different job).
• Ceramic disc tap — single quarter-turn handle. Needs a ceramic disc cartridge (different again).

If your tap is a mixer or ceramic disc, the washer won't fix it. Stop here and read our how-to-fix-a-leaking-tap guide for the cartridge process.

The rest of this article assumes you have a compression tap.

Short answer: yes, in your own home. Under Victorian plumbing regulations (Plumbing Regulations 2018 + Building Act 1993), tap washer replacement on an existing tap is treated as minor maintenance — not regulated plumbing work. An owner-occupier can do it in their principal place of residence without a plumber's licence.

Where the law draws the line:

• Owner-occupiers in their own home — fine to DIY washer replacement, gland packing, jumper valve swap on existing taps
• Rental properties — landlord must engage a licensed plumber even for minor repairs. Tenants should not DIY without landlord approval, and insurance / warranty cover usually requires a licensed tradesperson regardless
• Commercial premises — must be a licensed plumber, no exceptions
• Body corporate common areas in apartment buildings — owners corporation engages a licensed plumber
• Anything beyond the washer — if the job ends up needing pipework cut, joined or replaced, a new tap installed, or any work on the supply line itself, that's regulated plumbing work and needs a BPC-licensed plumber. Stop and call one.

One insurance gotcha worth knowing: if a DIY tap repair fails and causes water damage, some home insurers will decline the claim on the basis the work wasn't done by a licensed tradesperson. Policies vary across Victorian insurers. Worth a 30-second check of your PDS before starting if the tap is on a line that could cause significant damage if it fails.

Step 1: Shut off the water supply

Look under the basin or sink for an isolation valve on the supply pipe — a small in-line tap. Turn it perpendicular to the pipe (off).

If there's no isolator, turn off the mains tap at the meter. If neither works cleanly, stop here — a plumber needs to fit an isolator before this job can be done safely.

Step 2: Drain the residual water

Open the tap you're working on fully so water trapped between the isolator and the tap drains out. A bit will continue to weep when you open the tap body — have the towel ready.

Step 3: Remove the handle

Most compression taps have a small button or decorative cap on top of the handle. Pop it off with a fingernail or a flat screwdriver. Underneath is a Phillips-head screw — undo it, lift the handle off.

If the handle is stuck (years of corrosion under the cap), give it a careful tap from below — never lever from the top, you'll crack it.

Step 4: Undo the gland nut

Under the handle is a hex-shaped gland nut holding the spindle assembly (the "headworks") in the tap body. Use the shifter to undo it anti-clockwise.

If it's stuck: a few drops of penetrating fluid (RP7 or similar) and 5 minutes wait usually does it. Don't apply heat near plastic components.

Step 5: Lift out the headworks

Once the gland nut is free, lift the spindle assembly straight up out of the body. You'll see the jumper valve at the bottom — a small brass cup-shaped piece — and the worn black rubber washer sitting inside it.

Step 6: Replace the washer

The washer is held in the jumper valve by a tiny central screw or by being pressed in.

For a screw-held washer: undo the screw with a small screwdriver, lift out the worn washer, drop the new one in (matching the same size), reinstate the screw firm but not over-tight.

For a press-fit washer: prise the old washer out with the corner of a screwdriver, press the new one in with your finger or the flat of the screwdriver until it seats evenly.

Most household compression taps in Australia use a 12mm or 15mm washer. Bring the old one to the shop if you're unsure — they're cheap.

Step 7: Inspect the valve seat

While the headworks is out, look down into the body of the tap with a torch. You should see a smooth brass ring at the bottom — the valve seat. The new washer presses against this when the tap is closed.

If the seat is smooth and round: you're good to reassemble.

If the seat is pitted, scratched or has a gritty ring around it: the washer can't seal against a damaged seat. You need a reseating tool (Bunnings, around $40-$60) to grind the seat smooth, OR the whole tap needs replacing. See the "When the washer fix won't last" section below.

Step 8: Reassemble

Lower the headworks back into the body, making sure the spindle goes into its original orientation. Tighten the gland nut firm but not crushing — over-tightening cracks the body or strips the threads.

Put the handle back on, tighten the Phillips screw, push the decorative cap back into place.

Step 9: Turn the water back on slowly

Open the isolator gradually so trapped air doesn't hammer the line. Open the tap, let it run for a few seconds to flush any debris, then close it tight.

Step 10: Test for drips

Wait a few minutes. Check the spout for drips (looks fine = washer is sealing). Check the gland nut and the base of the tap for weeps (looks fine = reassembly is right).

If a drip remains: see troubleshooting below.

When to stop DIY-ing and call a plumber

Five signs a washer replacement won't be the right fix on its own:

• The tap body looks corroded inside when you open it — repairs on a failing body waste the parts; replace the whole tap instead.
• Multiple taps in the house are leaking at the same time — likely an over-pressure issue (mains pressure too high). System-level fix needed, not per-tap.
• The valve seat needs reseating but you've never done it — a first attempt with the reseating tool at the wrong angle can make the seat worse and ruin the tap body.
• You've replaced the washer twice and it keeps failing — either wrong washer size or the valve seat is damaged. Needs proper diagnosis.
• The leak is at the base of the tap, not the spout — different problem entirely. Usually the compression nut underneath has loosened or the mounting seal has perished.

A plumber typically charges $150-$280 to fix a leaking tap, including the diagnosis. Multi-tap jobs in the same visit attract a per-tap discount.

When you'd rather just call us

Reading this and thinking "I'll book a plumber instead" is a perfectly reasonable call. Most leaking tap repair jobs are under an hour, fixed-price quote at the door, and we carry the standard Australian washer + cartridge sizes on the van.

Call 0475 407 670 or send your address through the contact form — we'll quote a fixed price before any work begins.

The most common reason a washer replacement doesn't fix a leak is a damaged valve seat.

The seat is the brass surface the washer presses against. Over decades of use, the seat develops:

• Tiny grooves where the washer has dug in
• Pitting from waterborne minerals (especially hard-water suburbs)
• Calcium build-up on the rim

A new washer pressing against a damaged seat will leak — sometimes immediately, sometimes after a few weeks.

The fix: use a reseating tool. It's a hand-operated grinding tool that fits into the tap body, sits over the seat, and grinds it smooth in 20-30 turns. Tools cost $40-$60 at Bunnings.

If the seat is too badly damaged to reseat: the tap needs replacing. A new mid-range compression tap is $40-$100 + an hour's install. Trying to keep an old tap going past this point becomes false economy.

1. Over-tightening the gland nut. Cracks the body or strips threads. Firm and stop. A drop of water from the gland nut after assembly = loosen slightly OR replace the gland packing.
2. Forgetting to drain the line first. Residual water sprays when you lift the headworks. Open the tap fully first.
3. Mixing up hot and cold handles after reassembly. Mark them when you start if you're worried — the handles look identical once they're off.
4. Wrong washer size. A washer that's too small won't seal, too large won't seat. Match the size — bring the old one to the shop.
5. Reassembling over a corroded seat without checking. New washer + bad seat = leak in 2 weeks. Inspect the seat with a torch every time.
6. Using PTFE tape on the gland nut. Not needed and can prevent proper sealing. The gland nut seals on the packing inside, not the threads.