Fixing a leaking mixer tap isn’t as difficult as it first seems. All it needed was some patience and a replacement cartridge costing less than £5.
The Mixer Unit
This is the pesky tap that has been leaking intermittently for no apparent reason. I had no idea how it was constructed, but Google gave me a good idea of what to expect and the rest of it was just a matter of having some patience.
Turn off the Water Supply
Unless you are in an old house you can normally find water disconnection joints in the two pipes leading to the tap. Turn them both off by aligning the screw slot perpendicular to the flow of water. If you leave the tap open with small water flow while you do it you will know when it’s properly disconnected.
Remove the Tap Cover
!! Note !!
Before you go any further, put a plug into the sink or you may lose small parts down the drain.
There will be hole in the head unit plugged by a soft-cover. The hole provides access to a screw that binds the head unit to the lever in the internal mixing unit. Sometimes the cover is disguised as a plastic label (eg: hot & cold symbol). Mine was plain grey and I simply pushed it into the hole and fished it out later.
Remove the Tap Head
The screw was made for a 2.5mm Allen key. With the tap disconnected from the sink and leaning forward, I could insert the Allen key and disconnect the head from the internal mixing unit.
If you are careful you can disconnect the head and still leave the screw in its housing, otherwise, you run the risk of dropping the screw.
Remove the Decorative Shroud
With the head removed, you can unscrew the decorative shroud anti-clockwise next.
Remove the Clamp
Now you can unscrew the clamp anti-clockwise.
Remove the Cartridge
The ceramic mixing unit (with a plastic body) can now be lifted clear of the tap. You can see how the two lower holes admit hot and cold water and the mixing happens in the unit.
Replace the Cartridge
I couldn’t get an exact replacement so I opted to try one that had the same dimensions and a similar pattern around the holes in its base. I didn’t have any trouble using a similar replacement.
Reassemble the Tap
Clamp the new mixer unit into place and before you assemble the head, gently turn on the water supply and try moving the nylon pillar by had to ensure there are no leaks and the mixing occurs as expected.
It’s worth adjusting the disconnection valves so that the maximum flow of water is to your liking. There’s no sense in putting it back to maximum flow if it gushes water inconveniently fast.
If the unit is working, all you need to do is replace the shroud, tap head and soft-cover and monitor its success for a few days.