Fitting a Bath / Shower Mixer Tap with Shower Head Holder

Both mix hot and cold water, usually through a ceramic cartridge controlled by a single lever. They differ mainly in the outlet and the fitting height.

• A bath mixer has a spout over the bath and a diverter that switches between bath and shower. It sits low on the wall, usually roughly 10 to 20 cm above the rim of the bath, so the water runs into the bath and does not splash around.
• A shower mixer has no spout. The water goes only to the hose and shower head. It is fitted higher, usually around 110 to 120 cm above the shower tray, so you can reach the lever without bending.
• A thermostatic mixer, for bath or shower, keeps the set temperature steady even when someone elsewhere in the home turns on a tap. It suits households with small children or older people well.

The height of the outlets is decided when the pipework goes in, before tiling. If the outlets are already in the wall, the mixer has to go on them. Moving them means opening up the pipework and the tiles.

The exposed wall-mounted mixer is very common in flats and older houses across Europe. It connects to two outlets in the wall, usually spaced 150 mm apart.

1. Turn off the water, open the old mixer and let the remaining pressure out.
2. If you are replacing a mixer, remove the old one and clean old sealant and limescale off the outlets.
3. Screw the offset (eccentric) connectors into the outlets, sealing the thread with PTFE tape or hemp and jointing paste.
4. Turn the connectors until their spacing matches the mixer exactly, they sit level, and the cover plates sit flush against the tiles.
5. Put flat washers into the mixer nuts and offer the mixer up dry first to check everything lines up.
6. Tighten the nuts with a smooth-jawed spanner or through a cloth so the chrome is not scratched.
7. Turn the water back on, check the joints and test hot, cold and the diverter.

Why two kinds of seal? The offset connectors seal on their thread, while the mixer seals on the flat washer under the nut. PTFE tape does not belong on the mixer nuts.

The shower head holder or slide rail is fitted last. It is screwed into wall plugs, ideally drilled into the tile rather than a grout joint. A tile bit and a gentle start without hammer action help avoid cracking the tile.

Deck-mounted mixer on the bath rim

This type goes into a hole in the bath rim or in the tiled surround. Underneath, it connects with flexible hoses to isolating valves. The job takes longer because the work is done in a tight space, and the valves must stay accessible, for example through an access panel in the bath panel. Freestanding baths have a floor-standing mixer with supply pipes coming up through the floor, and these must be prepared in advance.

Concealed mixer

The mixer body is built into the wall before tiling. Its depth has to be set according to the manufacturer so that it ends up flush with the finished tiles. Before the wall is closed, the pipework must be pressure-tested. After tiling, only the visible parts are fitted: the cover plate, lever and shower head or spout. The plumber and the tiler need to work together here. If the body is set too deep or too shallow, the cover plate will not sit properly, and this usually cannot be fixed without opening the tiling.

• Easier: swapping a wall-mounted mixer for a similar type, new outlets at the right spacing and height, flat tiling with nothing in the way.
• Harder: corroded or furred-up outlets, damaged threads, spacing so far off that offset connectors cannot correct it, or outlets set too deep or sticking out too far from the tiles.
• Most work: deck-mounted mixers connected under the bath rim, concealed systems, and cases where pipework has to be altered or tiles cut out.

In a block of flats you sometimes cannot shut off the water just for your own flat. The riser then has to be closed, which needs agreeing in advance with the building management or owners' association. Changes to pipework or outlet positions are a job for a plumber. For a larger bathroom refurbishment, check with your local building authority whether anything needs to be notified.

A handy homeowner can swap a wall-mounted mixer for a new one with the same spacing. If the outlets are damaged or need moving, call a plumber.

1. Turn off the water supply to the home and open the mixer to release the pressure.
2. Lay a cloth under the mixer and a towel in the bath so a dropped tool does not chip the enamel.
3. Loosen the nuts of the old mixer and take it off.
4. Check the offset connectors: if they are furred up or leaking, unscrew them, clean the threads in the outlets and fit new ones with fresh sealing.
5. Set the connector spacing to suit the new mixer and check with a spirit level that they are level.
6. Fit the cover plates, put new flat washers in the nuts and screw the mixer on by hand.
7. Tighten the nuts through a cloth, evenly and without great force.
8. Turn the water on slowly and watch all joints for a few minutes.
9. Attach the shower hose and test the diverter, hot and cold.
10. Check the joints again the next day, as a small weep often shows up only later.

• Overtightened nuts. The flat washer gets squeezed out and the nut can crack. The washer makes the seal, not the force.
• Hot and cold swapped. Facing the mixer, hot is normally on the left. On a thermostatic mixer, swapped supplies mean the thermostat will not work.
• Mixer crooked or off centre. On a bath, a sloping spout looks untidy and water may splash outside.
• Cover plates not sitting on the tiles. Water and dirt get behind them. The cause is poorly set connectors or outlets at the wrong depth.
• Debris in the pipes. After building work there is often grit in the pipework, which clogs the filters and damages the cartridge. Flushing the pipes before fitting is a sensible step.

• The mixer is level, centred and firmly fixed
• The cover plates sit on the tiles without gaps
• No joint drips, even at full flow
• Hot water is on the side marked red
• The lever moves smoothly and the temperature adjusts gradually
• The bath/shower diverter switches fully, without leaking into the other outlet
• The shower hose does not leak at either end and the shower head holder is firm
• On a thermostatic mixer, the temperature limiter works
• The area is clean and neither the tiles nor the bath are damaged