To replace a kitchen tap cartridge, isolate the supply, remove the handle and shroud, swap the cartridge, then reassemble and test.
Got a drip, stiff movement, or a handle that no longer lines up? A worn cartridge is the usual culprit in modern mixers. You’ll see how to isolate water, strip the handle, lift the old part, and fit the new one without damaging seals or finishes.
Changing A Kitchen Mixer Cartridge: Step-By-Step
Most single-lever and dual-lever mixers use ceramic discs inside a compact body. The process below works for many brands. Some details vary, so keep the tap’s manual handy. If not, take photos as you go.
Prep And Safety First
Clear the sink, lay a towel to protect the surface, and place a plug in the waste to catch small screws. Turn the water off at the service valves under the sink; turn both clockwise until the flow stops at the spout. If you can’t find isolation valves, shut the property’s stop tap and drain the line by opening the tap.
Tools And Materials
Use a wrench that fits the retaining nut snugly and a properly sized Allen key for the handle screw. Silicone grease helps the new seals seat without tearing.
| Item | Purpose | Notes |
|---|---|---|
| Allen key or screwdriver | Release handle screw or cap | Common sizes: 2–3 mm hex |
| Adjustable wrench or socket | Undo cartridge retaining nut | Keep jaws square to avoid scuffs |
| Small flat blade | Pry the decorative cap | Wrap tip with tape to protect finish |
| Pliers | Lift stubborn cartridge | Grip the stem, not the body |
| Silicone grease | Lubricate O-rings | Use a potable-water grade |
| White vinegar or descaler | Clean limescale in the seat | Rinse well after treatment |
| Replacement cartridge | Restore smooth control | Match size, spline, and brand |
| Towels and a bowl | Catch drips | Protects cabinetry |
Step 1: Isolate And Drain
Turn hot and cold valves under the sink clockwise to shut water. Open the tap at the sink to relieve pressure and confirm the supply is off. Leave it open until the flow stops.
Step 2: Remove The Handle
Pop the small hot/cold cap with a taped flat blade. Loosen the grub screw inside with the correct hex key. Lift the handle straight up. If there’s a decorative shroud, unscrew it by hand.
Step 3: Expose And Loosen The Retaining Nut
You’ll see a large nut or collar above the body. Fit a wrench or a 32 mm socket, keep it square, and back it off. Some taps have a horseshoe clip instead; pull it out with pliers.
Step 4: Pull The Old Cartridge
Grip the stem and pull straight up. Mineral build-up can hold it tight. A gentle twist frees the O-rings. Check the body for debris and rinse. Inspect the seat for chips; any damage can cause ongoing drips.
Step 5: Match The New Part
Cartridges look similar, but sizing matters. Measure the diameter (commonly 25 mm, 28 mm, or 35 mm), the height, and the number of splines if you have dual-lever valves. Compare the tab shape and locating pins. If your old part has a brand code, use it to source a direct replacement.
Step 6: Fit, Grease, And Reassemble
Lightly grease O-rings. Align the locating tabs with slots in the body and press the new cartridge home. Thread the retaining nut by hand to avoid cross-threading, then snug it with the wrench. Refit the shroud, handle, and cap.
Step 7: Turn Water On And Test
Crack the valves open slowly. Check for leaks at the base and around the handle while cycling left/right and up/down at once. If hot and cold feel reversed, lift the handle off, rotate the stem 180°, and refit.
How To Identify The Right Replacement
A correct match saves repeat work. Start with brand, then measure. If the label is missing, compare pictures on the retailer’s listing or a parts catalogue. Look at tab pattern, stem shape, and any color markers.
Common Sizes And Clues
Single-lever mixers often use 35 mm or 40 mm cartridges. Compact bar mixers may use 25–28 mm. Two-handle mixers use separate hot and cold valves with a toothed stem; the spline count and stem shape need to match or the handle won’t seat.
When The Cartridge Isn’t The Only Issue
If the spout drips after a new part, examine the aerator for grit. If the handle still feels tight, check for scale on the retaining nut or in the body. A cracked body or worn seat calls for a new tap rather than another cartridge.
Pro Tips For A Smooth Swap
Protect The Finish
Use painter’s tape on jaws and around the shroud so tools don’t scar chrome. Work with steady pressure. Sudden moves tend to mar soft trims.
Mark Handle Position
Before lifting the handle, snap a quick photo of the alignment. It makes the final position easy to set when you refit the lever.
De-scale The Seat
Soak the cavity with vinegar for a few minutes to loosen mineral scale, then rinse and wipe. A clean seat helps O-rings seal and keeps the action smooth.
Use The Right Grease
A thin smear of silicone grease on O-rings reduces friction and prevents pinched seals. Petroleum grease swells rubber, so avoid it.
Reference Steps From Leading Brands
Manufacturers publish clear steps for many models. A typical single-lever guide shows: remove the cover, back out the 3 mm grub screw, lift the lever, unscrew the 32 mm retaining nut, pull the cartridge, insert the new one, and reassemble in reverse.
When To Call A Plumber
Book a pro if the stop tap won’t close, the body is seized, or the tap is built into a fragile countertop. Also call in help if you find corrosion, stripped threads, or a cracked casting during teardown.
Troubleshooting After Replacement
| Symptom | Likely Cause | Fix |
|---|---|---|
| Drip at spout | Debris on disc or seat | Flush, re-seat, or replace faulty part |
| Leak under handle | Mis-seated O-ring | Re-grease and refit correctly |
| Handle squeaks | Dry seals | Add a light silicone grease film |
| Reversed hot/cold | Stem orientation | Lift handle and rotate stem 180° |
| Low flow | Clogged aerator | Clean or replace aerator |
| Hard to move | Scale in body | De-scale cavity and nut |
Cost, Time, And When Replacement Beats Repair
Most swaps take half an hour once you have the part. A budget cartridge costs less than a full tap, and it keeps a good spout and finish in service. Replace the tap when the body is cracked, the mounting is loose, or parts are no longer available.
Water Shutoff Basics You Should Know
Under-sink valves save time. If they’re missing or stuck, close the internal stop tap near where the supply enters the property. Turn clockwise to shut water, and reopen it slowly after the job to avoid hammer and sudden surges.
Care After The Swap
Once the new part beds in, cycle the lever through full range a few times a week. This keeps deposits from building at the travel ends. Wipe trims with a mild cleaner and a soft cloth.
Quick Part-Sourcing Checklist
Before you buy, gather a clear photo of the old part, rough dimensions, and brand details. Take the old cartridge to the store, or match it with a technical sheet online. Many maker catalogues show exploded diagrams with the exact spare number you need.
Identify Isolation Valves And Stop Taps
If you’re unsure about the shutoff points, look for small quarter-turn valves on the hot and cold pipes under the sink. The slot across the head lines with the pipe when open; turn it a quarter turn so it sits across the pipe to close. If those valves are missing or seized, use the internal stop tap and reopen slowly after the work. See how to turn the water off for safe shutoff steps.
Model-Specific Notes From Makers
Brand instructions differ in small ways. A typical single-lever mixer uses a pop-off cover, a 3 mm grub screw, a hand-spun shroud, and a large retaining nut. After pulling the old unit, drop in the new one with tabs aligned, snug the nut, and refit the lever. Many brand guides show this exact order with clear photos. See change a basin mixer cartridge for a photo sequence from a major maker.
What’s Inside A Ceramic Cartridge
Two polished discs slide against each other to meter water. The lever moves the top disc across ports in the fixed disc to set flow and blend hot and cold. O-rings seal the body. Chips or grit on the seat cause drips, so flush the cavity and wipe it clean.
Stuck Parts And Gentle Persuasion
If the retaining nut resists, add penetrating oil and give it time. A strap wrench grips round shrouds without marks. When a U-clip holds the cartridge, pull it straight up; bending a clip can score the valve body.
Frequent Mistakes To Avoid
Over-tightening: snug beats brute force. Crushing seals makes the action stiff and shortens life.
Wrong handed parts: some twin-valve mixers need left- and right-hand cartridges. If handles turn the wrong way, swap sides or source handed parts.
Skipping a flush: with the cartridge out, briefly open the valves to purge grit, then close and refit.