How to replace a dripping faucet cartridge in a single-handle faucet
A dripping single-handle faucet wastes water, leaves the basin wet and can hide damage to the surrounding cabinet. In most cases, the culprit is a worn cartridge, a failed seal or debris caught against a ceramic disc. Replacing the faulty part is usually cheaper and faster than replacing the entire mixer.
The job becomes straightforward when the correct cartridge is available. Identify the faucet brand and model before ordering, isolate the water properly and work carefully around the retaining nut. Australian plumbing rules vary by state, council and strata complex, so check what DIY work is permitted in your area.
Identify the faucet and cartridge before buying
Start by examining the handle, body and any stamped or moulded markings. Photograph the faucet from several angles and take measurements with a ruler. The cartridge must match not only the tap’s diameter but also its height, connection arrangement and handle fitting.
| Faucet mechanism | Common clue | Part usually replaced | Critical matching detail |
|---|---|---|---|
| Ceramic disc | Smooth lever action with a drip from the spout | Complete ceramic cartridge | Diameter, length and spline count |
| Washer and seat | Common in older single-lever mixers | Rubber washer or seat | Thread size and washer dimensions |
| Ball cartridge | Rounded internal mechanism within a larger body | Ball, seals and retaining components | Ball diameter and seat arrangement |
| Proprietary mixer cartridge | Brand-specific replacement supplied as one unit | Complete cartridge | Exact model or part number |
The faucet may not reveal its type until the handle is removed. Avoid buying a “universal” cartridge based on diameter alone. Bunnings and Mitre 10 stock common components, while Reece and specialist plumbing suppliers are more useful for cartridges from less familiar brands. Australian-made or commonly stocked brands such as Dorf and Phoenix may also be available, although fittings still vary between ranges.
Look for the Australian WaterMark mark or confirmation that the replacement part is suitable for compliant Australian plumbing use. The old cartridge can also help a supplier identify the correct item, so take it along when possible rather than relying on a generic internet photo.
Gather tools and isolate the water
Tools and supplies
- Adjustable spanner, plus a basin wrench if space under the sink is tight
- Screwdrivers matching the handle’s set or retaining screws
- Old towel, small bucket and toothbrush for catching water and cleaning debris
- Penetrating oil and manufacturer-approved silicone lubricant, where needed
Locate the hot and cold isolation valves beneath the basin. Turn both clockwise until they close, then open a tap to release pressure. If there are no local isolation valves, use the property’s main stopcock. Older Sydney and Melbourne terraces and rental properties across Australia may have concealed or awkwardly positioned valves, so allow extra time to find them.
Never work on the faucet while water continues to flow through it. If the main stopcock cannot be found or closed, contact the landlord, building manager or a licensed plumber. Plug the sink waste, keep electrical appliances away from the wet work area and place towels beneath the faucet before dismantling it.
Remove the old cartridge safely
Single-handle mixers are usually secured by a grub screw beneath the lever or by a small retaining cap. Move the handle as directed by the manufacturer—often to its centre position—to expose the screw. Remove the screw, lift or pull off the handle and leave the trim pieces together in a labelled container.
The cartridge itself may be held by a large retaining nut, a snap-fit clip or a combination of both. Fit an adjustable spanner carefully to the flats of the retaining nut and loosen it slowly. A basin wrench can provide extra leverage without damaging the faucet finish. If the nut resists, apply penetrating oil around its threads and allow it to soak rather than applying sudden force.
Do not use pliers to crush the cartridge or grip the ceramic discs. Ease the unit out with a slight twisting motion, keeping it level so fragments do not remain in the valve body. If it will not move, stop rather than cracking the body; a plumber may be needed to free a seized cartridge or repair damaged threads.
Before cleaning, note the cartridge’s orientation and the position of the hot and cold connections. Check the ceramic discs for scoring, chipped edges and trapped grit. Inspect the rubber O-rings and seals for flattening, splitting or a loose fit.
Fit the replacement and rebuild the faucet
Clean the empty valve body with a toothbrush and flush it with water. Remove any hard-water crust, thread debris or fragments of the old seals. A blocked body can prevent even a new cartridge from sealing properly, especially in areas such as Perth where mineral deposits build up quickly.
Fit any supplied O-rings and lubricate rubber seals lightly with silicone lubricant approved by the manufacturer. Petroleum-based oils and cooking oils can swell or contaminate some seals. Do not apply lubricant to ceramic surfaces unless the cartridge instructions specifically permit it.
Insert the new cartridge in the same orientation as the old one. Its ports must align with the hot and cold supplies, and any locating tab must sit in the correct groove. Check that the handle position, travel and flow restrictor will operate properly once the retaining nut is tightened. A cartridge installed at the wrong angle may seem to work but continue to drip or deliver poor temperature control.
Secure the retaining nut by hand first, then tighten it with a spanner until firm. Avoid over-tightening, which can split a brass body or distort a ceramic disc. Reassemble the handle without forcing the lever onto the cartridge stem. Restore the water slowly and check immediately for leakage around the base and retaining nut.
Test the tap through its full movement at both temperatures. Then close it completely and wipe the spout dry. A properly fitted cartridge should stop the flow without the handle needing to be held in an awkward position.
Troubleshoot a drip that remains
First identify where the water appears. A drip from the spout usually points to the cartridge or outlet insert, while water around the base can indicate a loose retaining nut, failed handle seal or an incorrectly adjusted cartridge. Residue left by an earlier leak can also make the origin difficult to judge.
Quick checks after reassembly
- Remove and clean the aerator or outlet insert, then test with the tap fully closed
- Confirm that the cartridge model, spline count and connections exactly match the valve body
- Reset the handle according to the manufacturer’s calibration instructions and check both temperature positions
- Inspect O-rings, retaining-nut threads and the faucet body for cracks or distortion
Do not tighten the cartridge repeatedly and hope the problem will disappear. If the correct part cannot be identified, the valve body is damaged or water continues to circulate when the handle is closed, replacement of the complete mixer may be more economical. In a rental property or strata apartment, report the leak to the agent or building manager before attempting more involved work.
A licensed plumber should also handle live-water repairs, corroded pipework or installations covered by insurance conditions. Plumbing licensing and DIY requirements differ between Australian states and councils, so local advice matters when the job exceeds a straightforward cartridge swap.
Put the tap back to work and stop the leak
Once the new cartridge is operating correctly, flush the faucet briefly and clean the spout with mild cleaner. Avoid abrasive products that can scratch the finish around the ceramic disc. Keep the original cartridge, its packaging or a clear photograph of the part number for future repairs, and avoid using the handle as leverage when cleaning the sink.
Check the isolation valves and supply connections while they are accessible. A valve that has begun to weep can sometimes be tightened slightly or serviced, but replacing a failed valve while the faucet is open can cause avoidable water damage. Keep a small washer kit or the plumber’s contact details nearby if the valves are old.
Make the final check now: run both temperatures, move the lever through its full range, close the tap firmly and wipe the spout dry. Check again after five minutes. A dry spout and a properly seated handle mean the repair is complete and the tap is ready for everyday use.