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How to change basin taps

How to Change Basin Taps: The Complete Plumbers Guide

Last updated on January 31st, 2024

Learning how to change basin taps, or ‘bathroom sink’ taps are pretty straightforward but if the tap is dripping, you might be be able to fix.

I have been a full-time plumber and replacing taps for over a decade, and I can tell you that the hardest part is removing the basin taps when they are really old and rusted or seized underneath.

If they are fairly new taps, then it should be simple.

Here I’ll give you my best advice for changing your old basin taps based on my everyday experience.

Basin Tap Fitting Tools

These are the basin tap fitting tools I need on most basin tap replacement jobs. Investing in the best plumbing tools will make fitting taps a lot easier, especially if you plan to do it regularly.

Tap tightening tool

If you have a basin mixer tap, then this is the same as changing a kitchen tap. You will need a monobloc tap spanner set as the nuts are always a different size, typically between 8 – 13 mm.

A standard tap backnut box spanner is 27 mm at one end and 32 mm at the other.

The 27 mm end will be suitable for changing single basin taps (separate hot and cold taps), and the 32 mm end will be suitable for changing bath taps.

If there are no flexible tap connectors on the old bath taps, then you will also need a 15 mm pipe cutter to cut the pipes and fit isolation valves for the new flexible tap connectors to connect to.

How to Remove Basin Taps

  • Isolate the water supply to the basin taps
  • Open the basin taps and the other taps in the property to get rid of the water from the pipes
  • Put a towel down under the basin taps to catch any water
  • SINGLE BASIN TAPS: Turn the nut on the bottom of the tap threads anti-clockwise with an adjustable spanner and pull flexible tap connectors to the side
  • BASIN MIXER TAPS: Hold the isolating valve with water pump pliers and turn the nut on top of the isolating valve and bottom of flexible tap connectors anti-clockwise with an adjustable spanner, and pull flexible tap connectors to the side
  • Cut the pipes if there aren’t any flexible tap connectors on the old taps
  • Push a backnut box spanner over the tap threads and over the backnuts securing them to the basin, and turn them anti-clockwise to unscrew and remove both backnuts
  • Pull the basin taps or basin mixer tap out of the holes
Removing basin taps with box spanner
Removing basin taps with box spanner

How to Fit Basin Taps

  1. Fit the new basin tap or taps into the holes in the basin with any foam or rubber seals supplied, and screw the backnuts on from underneath
  2. Tighten with the backnut tap tightening tool – the small end of the box spanner
  3. Screw on the flexible tap connectors to the tap threads and tighten with an adjustable spanner
  4. If you had to cut the pipes, then you should fit some new flexible tap connectors
  5. Close all the taps in the property and turn the water supply back on and check for leaks

How to Change Basin Tap Parts

Replacing basin tap parts is possible when you have problems with them, you don’t always need to change the tap.

How to Change a Basin Tap Head

To change a basin tap head, you need to find the screw keeping it fixed to the basin tap.

This is normally covered with a plastic cap which can be screwed off or pulled off with a small flathead screwdriver.

Once this is removed, you can loosen the screw holding the head on the tap. This is normally a grub screw that takes a 2.5 mm Allen key on a basin mixer tap, or a cross-head screw on single bathroom taps.

Once this is loose, the head or handle should just pull off the basin tap. Then fit the new basin tap head and fix it with the screw.

How to Change a Basin Tap Cartridge

To change a basin tap cartridge, you need to remove the head or handle as above, and then you will need to unscrew the brass cartridge anti-clockwise using an adjustable spanner on single basin taps.

You might need to hold the tap still with some large water pump pliers or a pipe wrench, whilst you turn the cartridge out. These can be very stiff on old basin tap cartridge replacements.

Once out, screw the new cartridges in and tighten them up with a spanner.

For single lever basin mixer taps, once you remove the handle, you need to unscrew the shroud and the tap cartridge should lift out. Fit new cartridge and refit shroud and handle.

How to Change a Basin Tap Washer

If you need to fix a dripping tap, then changing the tap washer might be a solution. You can only change a basin tap washer on full-turn taps.

That full-turn tap is when you have to turn the tap head a few times for it to let the water out as fast as it will come.

If you have quarter-turn or half-turn taps, you will not be able to replace the washer as they don’t have washers, they have ceramic discs.

If you have full-turn basin taps, then you will need to remove the tap cartridges as above, and then replace the washer with the exact same washer. Then refit the cartridge and the tap head.

The correct washers can be hard to find. I would recommend replacing the cartridges over replacing the washers.


Changing basin taps is straightforward most of the time. The biggest problem I have is loosening the old rusty nuts on the tap connectors, especially on copper pipes.

They are the easiest taps to change as they are the easiest to access.

Having the best plumbing tools will help things go better and if you're struggling to loosen nuts use bigger tools to get more leverage.

Feel free to ask me any questions in the comment section below and I’ll try my best to help.

Please share this post if you find it helpful.


What size box spanner for basin taps?

The box spanner size needed for single (separate hot and cold) basin taps is 27 mm.

You can buy a backnut box spanner with 27 mm at one end for basin tap backnuts, and 32 mm at the other end for bath tap backnuts.

For basin mixer taps, the small nut sizes vary.

A monobloc tap spanner set with 3 box spanners will fit most nuts on monobloc kitchen and bathroom basin taps. The 3 box spanners have 6 sizes, from 8 mm up to 13 mm.

Is it easy to change basin taps?

No, it’s not easy to change basin taps. It’s easier to change basin taps than other taps most of the time, but it’s not easy to do unless you have done it before.


  • Steven Reid

    I am a full-time plumber and Gas Safe registered engineer. I incorporated Housewarm Ltd. in 2011 to provide heating and plumbing services to homes in Newcastle upon Tyne, England. I now blog about what I've learned over the years to help DIYers and plumbers.

    View all posts
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