Fitting a Water Tap

All these taps do the same thing: they mix hot and cold water. They differ in size, in how they are fixed and in what needs attention during fitting.

• A deck-mounted basin mixer is small and compact. It sits in the tap hole of the basin and connects to the isolating valves with flexible hoses. A countertop or vessel basin needs a taller tap or a wall-mounted one. Otherwise the spout does not reach over the bowl.
• A kitchen sink mixer is usually taller, with a longer swivel spout and often a pull-out spray. It goes into the sink or straight into the worktop. Worktop thickness matters here, because the fixing studs must be long enough. With a pull-out spray you need free space in the cupboard below for the hose and its weight.
• A wall-mounted mixer screws directly onto the outlets in the wall. The outlets are usually about 150 mm apart. Small differences are taken up by offset (eccentric) connectors.
• A concealed mixer has its body hidden in the wall, so you only see the controls. The body goes in before tiling, so it has to be planned together with the tiler.

When choosing, look at the cartridge and the body material as well. A ceramic cartridge moves smoothly and usually lasts a long time. A brass or stainless steel body holds up better than cheap alloys. Before you buy, measure the tap hole in the basin or sink, the spout length and the height under the spout. The spout should point to the middle of the bowl. At the kitchen sink you want enough room to fill a tall pan.

The same job can take a few minutes in one home and turn into a longer piece of work in another. Fitting takes longer when:

• there are no isolating valves, or they are seized and will not shut off the water. In a flat this can mean turning off the water to the whole riser, which you arrange with the building management or owners' association,
• the old nuts are corroded and the old tap has to be worked loose,
• access is poor, for example deep in a kitchen cupboard behind the waste pipe, a bin and the sink bowl,
• it is a new installation where a hole has to be drilled in the worktop or new valves fitted,
• the wall outlets are in the wrong place in spacing or height, or you are swapping a wall tap for a deck tap or the other way round. Then the pipework has to be altered.

The simplest case is swapping a deck-mounted tap for a similar one where the isolating valves work.

If your isolating valves work and the new tap is deck-mounted, you can do the swap yourself. Have an adjustable spanner, a bucket, a cloth, a torch and new seals ready. If the tap comes without hoses, buy good quality braided stainless steel hoses in the right length.

1. Close the isolating valves and open the tap to let the remaining water run out.
2. Put a bucket underneath and disconnect the hoses from the valves.
3. Loosen the fixing nut under the basin or sink and lift out the old tap.
4. Clean limescale and old sealant from around the hole and check the threads on the valves.
5. Screw the hoses into the new tap by hand and nip them up gently as the manufacturer describes.
6. Place the seal under the base of the tap and feed the hoses through the hole.
7. Fit the washer and nut from below, line the tap up and tighten it until it no longer wobbles. Do not force it on ceramic.
8. Connect the hoses to the valves: hot on the left, cold on the right. Keep the hoses free of kinks, crossings and tension.
9. Open the valves slowly and wipe every joint with a dry paper towel.
10. Run the lever through the full range of temperature and flow, then watch under the basin for a few minutes for any drip.

Hoses with a rubber seal on the end need no tape. PTFE tape or hemp is only for tapered threads that have no seal.

A handy homeowner can fit a wall-mounted mixer onto existing outlets, usually about 150 mm apart. First the offset connectors are screwed into the outlets and sealed with hemp or PTFE tape. Their spacing and depth are set so the cover plates sit flat against the tiles. The tap is then screwed on over flat washers and levelled with a spirit level.

If the outlets have to move, walls have to be opened or a concealed mixer is going in, this is a job for a plumber. The concealed body must sit at the exact depth the manufacturer gives, so the controls end up flush with the finished tiles. The pipework needs a pressure test before it is covered. The tiler then leaves accurate cut-outs for the controls. If shared pipework in a block of flats is affected, speak to the building management first. For bigger alterations, check with your local building authority whether any notification or approval is needed.

• Reusing old seals from the previous tap. Always use new ones.
• Overtightening. Too much force crushes the seal or cracks the nut. Too little leads to a slow drip that often goes unnoticed until the cupboard base swells.
• Hot and cold swapped. An ordinary mixer then works the wrong way round, and a thermostatic one will not regulate properly.
• Twisted or stretched hoses. They wear over time and can burst.
• Dirt in the pipes. After the water has been off, sand or rust can get into the tap and block the aerator. A short flush before connecting helps.
• Silicone instead of a seal. A bead of sealant around the base can add protection, but it does not replace the seal.

Go through the work straight away, while the tradesperson is still there:

• The tap is firm and does not wobble or turn when you move the lever
• All joints under the basin or sink are dry after a few minutes of running
• Hot is on the left and the lever moves smoothly through the full temperature range
• The spout points to the middle of the basin or sink and water does not splash outside
• The hoses have no kinks and the isolating valves close and open
• On a kitchen mixer, the pull-out spray slides out easily and returns by itself
• On a wall-mounted tap, the cover plates sit flat on the tiles and the tap is level
• The area is clean and you have the instructions, the guarantee and any spare parts from the box