Leaking or stiff mixer tap: should you replace the cartridge?

A dripping mixer does not always need a completely new tap.

The answer in 2 lines. A persistent drip from a closed mixer tap can come from a worn or dirty ceramic cartridge. A stiff handle can also indicate a problem inside the mechanism, but weak flow or unreliable hot water may have another cause. Identify the tap and obtain its maintenance instructions before taking it apart. Isolate both supplies and check that flow has stopped. If you rent, report the fault to your landlord before arranging or attempting repairs.

The first steps

Find the source: dry the tap and surrounding area, then distinguish a drip from the spout from water escaping around the handle or underneath.
Identify the model: photograph the tap and look for an installation leaflet or identifying details. These help establish the correct cartridge.
Before dismantling: isolate the hot and cold supplies, open the tap and confirm that flow stops. Do not assume closing the mains stop tap isolates every hot-water arrangement.

Stop: danger

Water still flowing after isolation: do not loosen the cartridge retaining nut. Have the supply arrangement checked by an approved plumber.
Uncontrolled leak: turn off the appropriate supply if safe and keep water away from electrical equipment. Stop using the tap until the leak is contained.

Is the cartridge really the problem?

A persistent drip from the spout while the handle is closed points towards the shut-off mechanism. In a ceramic mixer, contamination or wear may prevent the cartridge sealing. A leak around the handle may involve its seals. These are clues, rather than a diagnosis.

Weak flow at this tap alone can involve the outlet aerator or another restriction. Hot water failing throughout the home calls for a wider check. A thermostatic shower valve is a different assembly: its servicing and temperature adjustment need the correct instructions. Use the WaterSafe Register dripping-tap guide to distinguish common tap mechanisms before choosing a repair.

What a cartridge replacement involves

The following is an outline, not a dismantling sequence for every mixer. With both supplies isolated and flow stopped, protect the basin and plug the waste so small parts cannot disappear. Photograph each stage.

Following the tap's instructions, remove the handle fixing and any cover that conceals the cartridge retaining nut.
Release the retaining arrangement and lift out the cartridge, noting its orientation and locating features.
Fit the specified replacement with its seals correctly positioned. A similar-looking cartridge is not proof of compatibility.
Reassemble to the specified tightness, restore the supplies carefully and check operation and leaks above and below the basin.

Stop if a fixing is seized, the tap body moves or the instructions do not match what you see. Do not improvise extra force on concealed pipework.

What not to do

Forcing a stiff lever or tightening the retaining nut excessively.
Buying solely by cartridge diameter: the stem, seals and locating features must also match.
Applying descaler, lubricant or abrasive cleaner inside the mechanism without checking the maintenance instructions.

Repair the cartridge or replace the tap?

A cartridge replacement is worth considering when the body is sound, the correct part is available and the mechanism can be accessed without damage. Cleaning may be appropriate if the instructions provide for it, but it cannot restore damaged sealing surfaces.

Consider a replacement tap when the body leaks, essential parts are unavailable or repeated repairs have failed. Ask for a written quotation describing the diagnosis, parts and labour. There is no reliable fixed price for every mixer: access, condition and the replacement part all matter.

Who arranges and pays?

In England, report a defective landlord-supplied tap in writing. Describe the leak and attach photographs. The GOV.UK repairs page explains landlord responsibilities for sanitary fittings and when tenants may undertake repairs. Ask for arrangements before dismantling or commissioning work; damage caused by occupants can affect responsibility.

Owner-occupiers normally arrange their own repair. If you need help, use the WaterSafe Register contractor search: enter your postcode and select a plumber working in your area. Describe the tap and isolation arrangements when requesting a quote.

Good to know

Keep the replacement part details and maintenance leaflet for future repairs.
Check again after using both hot and cold water: an initially dry connection can still need attention.
The tenancy guidance here is for England. Wales, Scotland and Northern Ireland have different housing frameworks.

Illustrative example: in Birmingham, Karim's kitchen mixer becomes stiff and keeps dripping. As a tenant, he sends photographs to his landlord instead of dismantling it. The arranged plumber identifies the cartridge, confirms the replacement and checks the isolation valves before fitting it. The tap body is sound, so the whole mixer does not need replacing.

A made-up story, for illustration.

Bobby

Sources, verification, confidence

Verified on 4 November 2026, for England. Confidence: high for reporting landlord-supplied sanitary fitting faults and using an approved contractor register; medium for symptom-based diagnosis and the general cartridge replacement outline. The exact tap instructions govern dismantling, compatible parts and tightening. No universal repair price or cartridge size is asserted.