How to fix a dripping mixer tap — the Australian guide
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If you searched for how to fix a dripping tap and every guide told you to replace the washer, that advice was wrong. Not because it was bad advice in general. Because there are no washers in a mixer tap.
Mixer taps use a cartridge, not a washer. The cartridge is a self-contained valve unit that the handle controls. When it wears out or the ceramic disc inside it cracks, the spout drips. Replacing a washer does nothing — because there is no washer to replace.
This is why the generic guides didn't help. You weren't doing it wrong. You were doing the right thing for the wrong type of tap. And now that you know what a mixer tap actually contains, the repair makes immediate sense.
This guide covers mixer taps specifically: how they work, why they drip, and how to replace the cartridge step by step. It also covers the part most guides skip — how to identify which cartridge you actually need before you buy one.
A mixer tap has one spout and one handle. You push the handle up or down to control flow, and side to side to control temperature. That single handle connects to a cartridge inside the tap body.
The cartridge contains two ceramic discs — an upper disc that the handle rotates, and a lower disc that sits fixed. When the handle is in the closed position, the discs align to block water. When you open the tap, the upper disc rotates, and the holes in both discs line up, allowing water through.
This ceramic-on-ceramic sealing system is more precise and longer-lasting than a rubber washer on a metal seat. But when one disc cracks — usually from high water pressure, sediment, or age — the seal fails. The tap drips even when the handle is fully closed.
One cartridge contains all the moving parts. Replace the cartridge, and you replace the sealing system entirely.
Understanding that mechanism also tells you exactly where to look when it fails — and why the failure is always somewhere inside the cartridge, not on a washer you can swap in two minutes. Here is what causes it.
The three most common causes of a dripping mixer tap:
A drip from the spout with the handle closed points to a disc or cartridge failure. A leak or weep around the base of the handle points to O-ring wear. Both involve the cartridge — but the replacement approach is the same.
Before you buy anything, you need the right tools in your hand.
What you'll need:
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Warning — before you order anything The most common mistake: ordering a cartridge online from a rough description, finding it doesn't fit, and waiting for a return and re-ship while the tap keeps dripping. This happens frequently. Cartridges are brand and model-specific. Read the cartridge identification section before purchasing anything. |
Find the isolation valve under the sink — a small valve on the cold water pipe below the tap. Turn it clockwise to close. If there's no isolation valve, turn off the mains at the water meter. Open the tap to release remaining pressure and confirm the water is fully off.
Most mixer tap handles have a decorative cap on the top or front — pry it off with a flat-head screwdriver. Underneath is a Phillips head screw. Remove it and lift the handle straight off the cartridge stem. Some handles pull off with a sharp upward tug; others need a gentle side-to-side rocking motion. Do not force.
Before you remove the retaining nut or disturb the cartridge, take a clear photo showing the cartridge orientation — which way the tabs face and how the locating lugs align with the slots in the tap body. You will need this photo when reinstalling.
Below the handle position, a retaining nut or collar holds the cartridge in place. Unscrew it anti-clockwise with your spanner. Once removed, the cartridge pulls or lifts straight out. Some slide out easily; others need a firm upward pull or slight rocking motion. Do not use a tool to lever them out — you risk damaging the tap body.
Apply a small amount of silicone plumber's grease to the O-rings on the new cartridge — not to the ceramic disc surfaces. Align the cartridge with the tap body using your reference photo. The locating lugs or tabs must sit correctly in their slots before the cartridge will seat fully. Press it firmly home by hand.
Replace the retaining nut clockwise — snug but not overtightened. Reattach the handle and secure the screw. Replace the decorative cap. Turn the isolation valve back on slowly. Test the tap through its full range: fully closed, partially open, fully open. Check for any drip from the spout and any weeping around the handle base.
Still dripping? Either the cartridge is the wrong size and hasn't seated correctly, or the problem isn't the cartridge. This guide covers the less common cause — but first, the cartridge identification problem.
This is where most DIY mixer tap repairs go wrong. Australia has no standard cartridge size. Caroma, Methven, Dorf, Greens, Rheem, Oliveri, Vado — every manufacturer uses different cartridge dimensions, different tab configurations, and different ceramic disc sizes. A cartridge that looks identical in a photo can be 5mm too wide or 3mm too short to seat in your tap body.
Three reliable methods for getting the right cartridge:
Method 1 — Take the old cartridge to a trade counter (most reliable).
Remove the old cartridge following Steps 1-4 above. Take it physically to a plumbing trade supplies counter — not a Bunnings, a trade supplier. Show them the cartridge and ask for a direct match. Trade suppliers stock a far wider range of cartridges than retail stores and can often match on sight.
Method 2 — Look up the tap brand and model.
The tap brand is usually engraved or embossed on the tap body — look near the base of the spout or on the back of the handle. Once you have the brand, a trade supplier can cross-reference the correct cartridge number. Caroma and Methven publish spare parts lists online.
Method 3 — Call your plumber.
Describe the tap brand, the tap age if known, and the cartridge dimensions — or simply bring the old cartridge in to your licensed plumber directly. On Time Plumbing can identify the correct replacement from the cartridge itself during a visit.
When calling a plumber for identification, note the tap brand (usually engraved on the body near the spout), the cartridge body diameter measured with a ruler, and the number and position of the locating lugs — this gives a trade supplier or plumber enough to source the correct replacement without a visit.
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From On Time Plumbing Many homeowners order the wrong cartridge online because mixer tap manufacturers use proprietary sizes. Always take the old cartridge to a trade counter for a physical match before ordering anything — it is the most reliable method available. |
We carry common Australian mixer tap cartridges and can fix your mixer tap the same day in Melbourne. Fixed price. No call-out fee during business hours.
Book a same-day mixer tap repair or Call us today at 1300 110 428.
If you've installed a confirmed correct cartridge and the tap is still dripping, the problem is not the cartridge. It is the tap body itself.
The tap body is the brass housing that holds the cartridge. Over time — or after a knock or excessive overtightening — the internal seat or the locating slots can crack or deform. A deformed seat prevents the cartridge from sealing fully, regardless of how good the cartridge is.
Two things to check if you reach this point:
Both diagnoses lead to the same conclusion: call your licensed plumber. A tap body fault is not fixable with parts from a hardware store.
Repair makes sense when the tap body is sound and the correct replacement cartridge is available. A new cartridge costs $20-$80, and the tap should perform like new after a successful replacement. It is almost always the right first step — cartridges are cheap, and if the fix works, the job is done in under an hour.
Full replacement makes sense when:
Your licensed tradesperson can assess this definitively at the time of the repair visit. If replacement is the recommendation, ask to see the specific component failure — any reputable plumber will show you.
You now know how a mixer tap works, why it drips, and how to replace the cartridge. You know how to identify the correct replacement before buying — the step that makes the difference between a repair that works and one that doesn't. And you know what to investigate if the cartridge swap doesn't fix the drip.
The generic guides didn't fail you because you were doing it wrong. They gave you washer advice for a washer tap. You have a mixer tap. The answer was always different.
Most mixer tap repairs in Melbourne homes take under an hour once you have the correct cartridge in hand. The cartridge identification step takes the longest — but it is the step that determines whether the repair works the first time.
Three possibilities. First, you installed the wrong cartridge — it may appear to seat correctly, but it is the wrong diameter or height, preventing a full seal. Second, the O-rings on the cartridge were installed without plumber's grease and have torn during installation. Third, the problem is the tap body, not the cartridge — a cracked seat or deformed locating slot prevents any cartridge from sealing. Check the cartridge size first. If you're confident it's correct, see the tap body section above.
A drip from the spout with the handle in the fully closed position almost always indicates a failed cartridge — either a cracked ceramic disc inside the cartridge, or a worn cartridge body that no longer compresses the disc properly. It can also indicate sediment damage to the disc surface. In rare cases, it indicates a fault in the tap body seat, but the cartridge is the right place to start.
Cartridge replacement in an existing mixer tap is allowable DIY work under Victorian plumbing regulations, provided the work doesn't involve disconnecting or modifying the supply pipes. The main challenge is sourcing the correct replacement cartridge, which requires removing the old one first and either taking it to a trade counter or getting it identified by your plumber. If the repair reveals a tap body fault, that assessment and any resulting work should be done by a licensed plumber.
Remove the old cartridge first — you cannot reliably identify it from the outside. Once removed, take it physically to a plumbing trade supplies counter for a direct match. Do not order online based on a description or forum photo — the size differences that prevent a cartridge from fitting are often invisible in photographs. If you cannot get to a trade counter, call a licensed plumber who can identify it during a visit.
Same-day availability across Melbourne. We carry the most common Australian mixer tap cartridges. Fixed price confirmed before we start.
Book a mixer tap repair or Call us today at 1300 110 428.
Disclaimer: DIY plumbing work carries risk. The instructions in this guide cover cartridge replacement in existing mixer taps under Victorian plumbing regulations. If you are uncertain at any step, stop and contact a licensed plumber. On Time Plumbing is not responsible for damage resulting from DIY work carried out without appropriate skill or in contravention of Victorian plumbing regulations.
