A leaking mixer tap is almost always a DIY-fixable job, and in most cases a worn ceramic cartridge or perished O-ring is the culprit. If you can isolate the water supply at the valves under the sink, replacing that cartridge or the O-rings typically solves the drip in around 15 to 20 minutes. Call a licensed plumber instead if you can’t isolate the supply, the tap body is cracked, or the leak returns after you’ve replaced parts.
TL;DR:
- Most leaks caused by worn cartridges or damaged O-rings can be fixed within 15 to 20 minutes by a DIYer, provided the water supply can be isolated easily.
- Properly identifying the leak point, such as the spout tip, base, or supply hoses, is crucial for selecting the correct repair part, like a cartridge or O-rings.
- Matching the replacement cartridge exactly to the model, including lug pattern and spindle shape, is essential to prevent quick failure or further damage.
- If leaks persist after a repair, check cartridge seating, ensure the O-rings are replaced, and examine for damage to the valve seat or damaged supply hoses.
- Major faults like cracked tap bodies or difficulty isolating water should be handled by a licensed plumber, especially if concealed pipework or water damage are involved.
Table of Contents
- Where is the mixer tap leaking from?
- What tools and parts do you need before starting?
- How do you replace the cartridge or O-rings step by step?
- Why does the tap still leak after a repair?
- When should you call a licensed plumber instead?
- How do you stop a mixer tap leaking again?
- What a plumber actually sees on these jobs
- When a DIY fix isn’t enough
- Sources
- FAQ
Where is the mixer tap leaking from?
Before you buy a single part, find out exactly where the water is escaping. A mixer tap has four common failure points, and each one points to a different fix.
Water dripping straight out of the spout, even with the handle fully off, almost always means the cartridge has worn out internally. Weeping or dampness around the base of the spout, where it swivels, usually means the spout O-rings have hardened or split. Water pooling under the sink cabinet is a different problem entirely: check the flexible supply hoses and their connection nuts before you touch the tap itself. A loose handle cap or a drip appearing only when the tap is in use can point to a worn seal inside the handle assembly.
Run a quick isolation test to confirm which side is bypassing. Turn off the hot isolation valve under the sink and watch the spout for 30 seconds. If the drip stops, the hot side cartridge or seal is the problem. Repeat with the cold valve isolated. This five-minute test saves you from replacing the wrong part.
| Symptom | Likely cause | What to check |
|---|---|---|
| Drip from spout tip | Worn ceramic cartridge | Isolate hot/cold to confirm side |
| Weeping at spout base | Perished spout O-rings | Look for wet residue where spout swivels |
| Water pooling under sink | Loose or damaged hose connection | Inspect flexi-hose swaged ends and nuts |
| Drip only when tap is used | Handle seal or worn cartridge | Check handle cap and grub screw area |
If you can’t locate an isolation valve under the sink at all, or the valve is seized and won’t turn, treat this as a more complex job before you go any further.
What tools and parts do you need before starting?
Getting the right gear together first stops a simple repair turning into three trips to the hardware store.
Tools:
- Adjustable spanner or ring spanner (correct size for the retaining nut)
- Allen key set (many handles use a hex grub screw)
- Flat and Phillips screwdrivers
- Needle-nose pliers for clips and retaining rings
- Soft cloth to protect chrome finishes from spanner marks
- Small container or tray to catch dropped screws and parts
Parts and consumables:
- A ceramic cartridge that matches your tap exactly
- Spout O-rings (buy a full set, not just one)
- Plumber’s tape for any threaded reconnections
- Food-grade silicone grease for O-rings and the cartridge housing
- A new aerator if the old one is scaled or damaged
Matching the cartridge correctly matters more than most DIYers expect. Lug pattern and spindle shape have to match exactly — a cartridge that physically fits the housing can still fail to seat or align properly, which means you’ll be pulling it apart again within days.
Pro Tip: Photograph the old cartridge from several angles and note any model numbers stamped on it before you remove it. Take that photo, or the cartridge itself, to a plumbing supplier rather than guessing from memory.
How do you replace the cartridge or O-rings step by step?
This sequence covers the two repairs that fix most mixer tap leaks: a cartridge swap for a dripping spout, and O-ring replacement for a weeping base.
- Isolate the water. Turn off both isolation valves under the sink. If you don’t have local isolation valves, you’ll need to shut the main supply instead, which is a sign this job may be better suited to a professional.
- Drain the pressure. Open the mixer fully and let any remaining water run out. Place a towel and a container underneath to catch drips during disassembly.
- Remove the handle. Pop off the decorative cap on top of the handle with a small screwdriver, then loosen the grub screw underneath. Lift the handle straight up without forcing it.
- Remove the shroud and retaining nut. Unscrew the decorative shroud, then use your spanner to loosen the retaining nut holding the cartridge in place. Photograph the cartridge’s orientation before you pull it, so reassembly is a matter of matching the picture rather than guessing.
- Extract the old cartridge. Lift it straight out. Inspect the housing for grit, scale, or scoring. Clean it out with a damp cloth if there’s build up.
- Fit the new cartridge. Align it to the locating lugs inside the housing exactly as the old one sat. Tighten the retaining nut snugly by hand, then a quarter turn with the spanner. Don’t overtighten. Ceramic discs only need light pressure to seal.
- Replace spout O-rings if the base is weeping. Lift the spout off its base (it usually pulls straight up once the retaining clip is released). Roll off the old O-rings, wipe the spout stem clean, and roll on new ones. Coat them lightly with silicone grease before re-seating the spout and clip.
- Service the aerator. Unscrew the aerator from the spout tip. Soak it in white vinegar for 20 to 30 minutes to dissolve scale, or replace it with a WaterMark or WELS-compliant aerator if it’s damaged.
- Reassemble in reverse order. Shroud, handle, decorative cap.
- Turn the isolation valves back on slowly, not fully open in one go. Slow, gradual opening lets air escape without hammering the new seals.
- Test every position. Run the tap hot, cold, and mixed, and check the base, spout, and underneath the sink for any sign of a leak.
- Keep the old cartridge and O-rings until you’re certain the repair has held for a few days.
- Don’t discard packaging until you’ve confirmed the new part fits and works.
Why does the tap still leak after a repair?
A new cartridge doesn’t always mean an instant fix, and there’s usually a specific reason why.
If the drip continues, first check that the cartridge is seated fully and the lugs are aligned correctly. A cartridge sitting slightly off its housing will never seal properly, no matter how tight you make the retaining nut. Confirm you actually replaced the spout O-rings and not just the cartridge. It’s a common mistake to fix one and skip the other when both were worn.
A scored or pitted valve seat inside the tap body is a harder problem. If you can see visible damage to the metal seat the cartridge sits against, no amount of cartridge swapping will stop the leak. That’s a job for specialised re-seating tools, which most homeowners don’t own and shouldn’t attempt to improvise.
Water pooling under the sink after a repair often has nothing to do with the tap itself. Check the flexible supply hoses for bulging, fraying, or a loose connection nut, and replace any hose showing wear rather than just re-tightening it.
- Never force a seized fitting. Excessive force on a corroded nut or spindle can crack the tap body entirely, turning a $30 repair into a full tap replacement.
- If a fitting won’t budge, apply a penetrating lubricant, wait 10 minutes, and try again gently.
Pro Tip: If you’re tightening the gland nut on an isolation valve to stop a drip there, a quarter turn is usually all it takes. Overtightening can crush the internal seal and turn a minor weep into a valve that won’t shut off at all.
When should you call a licensed plumber instead?
Some faults sit outside the scope of a confident DIY repair, and pushing through them tends to cost more than calling for help upfront.
- You can’t isolate the water supply locally, or the fault involves concealed pipework behind walls or under the floor.
- The tap body itself is cracked, heavily corroded, or the valve seat is visibly damaged.
- The leak persists after you’ve replaced the cartridge and O-rings correctly.
- You’ve noticed water staining, swelling, or damage in the cabinet or wall behind the tap.
- The job requires soldering, altering pipework, or re-seating a valve seat with specialised tools.
If you do call someone in, verify their licence through the official NSW register before work starts. It takes thirty seconds and confirms you’re not handing a burst pipe or a compliance issue to someone unqualified. Our guide on what to look for in a professional plumber covers what a genuinely reliable trade should offer beyond just a licence number.
How do you stop a mixer tap leaking again?
A little regular attention keeps a repaired tap working for years rather than months.
- Clean the aerator every six months to stop mineral scale building up and forcing the tap to work harder than it should.
- Wipe around the base of the spout occasionally. Catching a weep early means an O-ring swap, not a full cartridge replacement.
- Go easy on the handle. Ceramic disc cartridges only need light pressure to shut off. Cranking them hard wears the discs faster.
- If pressure feels unusually strong throughout the house, a pressure-limiting valve reduces the strain on every tap, not just this one.
- Replace flexible supply hoses proactively if you notice any bulging or fraying, rather than waiting for them to fail.
Fixing leaks and maintaining fittings properly also keeps your water bill in check. A dripping mixer left unchecked can waste thousands of litres a year, quietly, in the background.
What a plumber actually sees on these jobs
Most mixer tap leaks that land on our bench have already had a go from the homeowner, and that’s usually a good sign, not a bad one. It means the easy diagnostic work is done, and what’s left is often the part that needed a professional anyway: a scored valve seat, a stripped fitting, or a tap body that’s simply reached the end of its life.
What surprises people most is how often the actual repair is quick once you’re on-site with the right stock cartridges and tools. A straightforward cartridge swap takes a licensed plumber roughly the same 15 to 20 minutes it’d take a confident DIYer, minus the trip to the hardware store to work out which cartridge fits. Where things go sideways is when a homeowner has already tried two or three mismatched cartridges before calling, and the housing itself has taken damage from repeated forcing.
If you do end up booking a call out, have your tap’s make and model ready, a photo of the leak location, and a rundown of what you’ve already tried. It saves time and often saves you the cost of a second visit.
— Peter Honey
When a DIY fix isn’t enough
Most mixer tap leaks are a weekend job with the right parts and a bit of patience. But some aren’t, and that’s exactly where Priority Plus Plumbing steps in. We’re not a call centre booking you in for next Tuesday. We’re a local Sutherland Shire and Sydney plumbing team that answers 24/7, quotes upfront before any work starts, and turns up with the diagnostic gear (including CCTV inspection where a leak points to something bigger than the tap itself) to fix it properly the first time.
If you’ve worked through this guide and the drip won’t quit, or you’ve spotted water damage that’s got you worried about what’s happening behind the wall, that’s the point to stop guessing and get someone qualified to look at it. Learning what actually counts as a plumbing emergency helps you decide how urgently to act, and from there, booking a Priority Plus Plumbing technician is a straightforward call away.
Sources
For further reading, RACV’s dripping tap guide and YourHome’s water efficiency advice cover safety basics well. Our own detailed tap repair guide walks through the process with more detail if you want a second reference alongside this one.
- How to fix a dripping tap: step-by-step guide for Australian homes | RACV
- How to Fix a Leaking Flick Mixer Tap: Easy Steps to DIY | Bright Renovation
- Reducing water use | YourHome
FAQ
How do you stop a mixer tap from dripping?
Replace the worn ceramic cartridge and spout O-rings, which fixes the vast majority of drips once you’ve correctly isolated the water supply and matched the cartridge to your tap model.
Why is my mixer tap leaking from underneath?
Leaking under the sink usually comes from a damaged flexible supply hose or a loose connection nut rather than the tap body itself, so check the hose ends before assuming the tap needs replacing.
How do you change a washer on a mixer tap?
Modern mixer taps use ceramic cartridges rather than traditional rubber washers, so the equivalent fix is removing the handle, shroud, and retaining nut, then swapping the old cartridge for a correctly matched new one.
Why is the mixer tap leaking?
Most leaks trace back to a worn ceramic cartridge, perished O-rings, a scaled aerator, or a damaged supply hose, and a simple isolation test on the hot and cold valves will tell you which one it is.
Can I fix a leaking mixer tap myself?
Yes, in most cases. If you can isolate the water at the valves under the sink and the tap body itself is undamaged, a cartridge or O-ring swap is well within reach of a confident DIYer with basic tools.