Register your business

Home / Advice / How do you change a tap cartridge, and when should a plumber do it?

How do you change a tap cartridge, and when should a plumber do it?

Changing a tap cartridge means turning off the water to the tap, taking off the handle and the retaining nut, and swapping the old cartridge for an identical one. The hard part is usually identifying the right replacement, so many people take the old cartridge to a merchant or ask a plumber.

Last reviewed:

By the QuoteZila editorial team. Editorial policy.

What is a tap cartridge?

A tap cartridge is the part inside a mixer or lever tap that controls the flow of water, and on many mixers the balance of hot and cold. Older pillar taps with crosshead handles often use a washer instead. Many modern taps use a ceramic disc cartridge, where two discs slide over each other to open and close the water path.

When a cartridge wears or gets clogged with scale, the tap may drip from the spout when it is off, feel stiff or rough, or stop mixing properly. Replacing the cartridge often fixes those problems without replacing the whole tap.

How can you tell it is the cartridge that has failed?

The symptoms point to the part:

  • A drip from the spout with the handle fully off. Often the cartridge, or a seal on it.
  • A stiff, gritty or loose handle. Often wear or scale inside the cartridge.
  • Water only hot or only cold on a mixer. Can be the cartridge, but can also be a problem with pressures or a valve elsewhere.
  • Water around the base of the tap. Usually a seal on the body, not the cartridge.
  • A leak under the sink. A connection or a flexible hose, which is a different job.

If you are not sure which one you have, take a short video of the problem. It saves a plumber time on the first visit.

What does changing a tap cartridge involve?

In outline, and for a typical lever mixer:

  1. Turn off the water to the tap, at a valve under the sink if there is one, and open the tap to release pressure.
  2. Put the plug in, so small screws cannot go down the drain.
  3. Remove the handle. There is often a small cap hiding a screw.
  4. Undo the shroud or retaining nut that holds the cartridge in.
  5. Lift out the old cartridge and note which way round it sat.
  6. Fit an identical replacement, refit the nut and handle, then turn the water back on slowly and check for leaks.

That is the simple version. In practice the retaining nut can be seized with scale, the handle screw can be corroded, and the tap body can be damaged by too much force. If anything resists, stop. A plumber can usually free a seized part without breaking the tap.

How do you get the right replacement cartridge?

This is where most of the time goes. Cartridges vary by diameter, length, the number of splines on the spindle, and whether the tap turns a quarter turn or a half turn. Many taps take a part made for that particular make and model.

The most reliable approach is to take the old cartridge out and match it, or to find the make and model of the tap from the paperwork or the maker's mark. If you cannot identify it, a plumber can often source the part, though it may mean a second visit.

When should you call a plumber instead?

Call a plumber when there is no working valve to stop the water at the tap, when the nut or handle will not move, when the tap is very old or the part is hard to identify, or when the leak is from somewhere other than the spout. WaterSafe runs a register of approved plumbers you can search by postcode [S1].

When you ask for quotes, say what the tap is, what it is doing, and whether you already have the replacement part. Citizens Advice suggests getting written quotes from at least three traders [S2]. Ask whether the price includes the cartridge, and what happens if the part has to be ordered.

Jobs you might post

These are examples, not taken from real job posts. "Our kitchen mixer tap drips from the spout even when it is off. Please replace the cartridge." Or: "The bathroom basin tap is very stiff and the handle wobbles. Repair or replace the tap." Or: "Two taps in a house in Nantwich need new cartridges, and we do not know the make."

Get quotes from local plumbers

Post the job with the tap, the problem and your postcode. Up to five matched local businesses can reply [QZ2]. QuoteZila is free for customers and local businesses [QZ1]. QuoteZila is starting in Cheshire, and anyone in the UK can post or register.

Honest status: QuoteZila is new. We're starting in Cheshire, beginning with Crewe, Nantwich and Sandbach, and growing area by area. Anyone in the UK can still post a job or register a business. How fast you get quotes depends on how many local businesses have joined near you. Businesses can register and receive jobs straight away. We don't check insurance, qualifications or registrations, so please check these yourself before you hire.

Posting a job is not open yet

See the plumbers page, the handymen page for small jobs, or the plumber cost guide for what goes into a plumber's quote.

Questions about tap cartridges

How do I know if my tap needs a new cartridge?

A mixer or lever tap that drips from the spout when it is fully off, feels stiff or gritty, or will not mix hot and cold properly may have a worn cartridge. A drip from around the base or under the sink is a different problem, often a seal or a connection, and is worth showing to a plumber.

Are tap cartridges universal?

No. Cartridges differ in size, spline count, length and whether they turn a quarter or a half turn. Many taps take a part made for that brand or model. Take the old cartridge with you, or give the plumber the make and model of the tap, so the replacement actually fits.

Do I need to turn off the water to change a cartridge?

Yes. Turn off the water to that tap before anything is undone, either at a valve under the sink or at the main stopcock, and open the tap to let the pressure out. If you cannot find a valve that stops the flow, that is a good moment to call a plumber rather than carry on.

How do I find a plumber who knows the water regulations?

WaterSafe runs a register of approved plumbers that you can search by postcode. Whoever you use, ask them to name the part they will fit and to say in the quote whether the price includes it.

Does QuoteZila check the plumbers who quote?

No. We don't check insurance, qualifications or registrations, so please check these yourself before you hire. You can report a quote or a business from your job page.

Related trades

Cost guides

Related pages

Sources

  1. QZ1: QuoteZila product fact. QuoteZila home and jobs-for-tradesmen copy.
  2. QZ2: QuoteZila product fact. QuoteZila terms and matching notes.
  3. S1: Find a local approved plumber, WaterSafe. Accessed 2026-10-25. https://www.watersafe.org.uk/
  4. S2: Before you get work done on your home, Citizens Advice. Accessed 2026-10-25. https://www.citizensadvice.org.uk/consumer/getting-home-improvements-done/before-you-get-building-work-done/