Connecting taps to basins, baths, and sinks

This article covers connecting taps to basins, baths and sinks - the type of taps covered are those with ½ and ¾ inch pipe connections including 2 hole mixer taps- single hole Mono Block mixer taps are covered in this other article.

Hand basins normally use taps with ½ inch (15mm) pipework and connections; baths and sinks usually use taps with ¾ inch (20mm) pipework and connections.

There is no universal standard for which water supply goes on which side of the unit; however by almost universal practice in the UK:

  • In the North, the hot water goes to the tap on the right of the unit while in the South, it goes on the left.

Whichever way round you fit your water supplies, it's usually a good idea to be consistent throughout a property.

The connectors and tails

Compression tap fitting
tap connector

Solder to tap fitting



Tap tail adaptor


The connection of the pipework to the taps uses pipe to tap fittings; these are available with either a compression and a solder joints onto the pipework - both use a screw fitting onto the tail ('tail' is the threaded part which goes through the unit, is secured by a nut underneath and to which the water supply is connected) of the tap and a fibre washer to make the seal.

It is often a good idea to use a short piece of pipe down from the taps to compression joints in the pipework where it can be easily reached; this will allow the short piece of pipe to be secured to the taps before the unit is put in place thus avoiding the often awkward job of connecting to the taps in a confined area; it will also make the job easier if the unit needs to be removed in future. Even if a solder joint type tap fitting is used, this short pipe with a compression fitting at the bottom makes the installation easier.

The length of the tail on taps does vary, if replacement taps have shorter tails than the original taps; 'tail adaptors' can be fitted to add a bit of length to avoid having to remake the original pipework.

Bendable pipe for pipework to tapsTo avoid having to makeup special pipework bends to join between the fixed pipework and the taps,flexible pipes can be used. The two most common types are hand bendable 'ribbed' copper pipe (as shown) and stainless steel braided hoses; different lengths are available. The 'ribbed' copper pipe type usually has a plain section at one end that can be joined to the rest of the pipework using either a solder or compression type fitting; the stainless steel braided hoses usually have a screw connector for the tap end and a compression fitting at the other end which fits to the end of a pipe.

Supply shut off valveShut-off valves are now a requirement for all new installations - when fitting replacement taps to existing fixtures, it's often worthwhile fitting them (as shown right) into the supply pipes to isolate the taps if required in future - they are especially useful where a tap is fed directly from a storage tank; alternatively, a gate valve could be added to the outlet of the tank so all taps fed from it can be isolated from the one gate valve.

Connecting the pipework

Connecting to taps

It is often easier to fit the taps to the unit and make the connections to them, before fitting the unit in place - often once the unit is in place,access to the taps underneath the unit can be very restricted (this will depend on the layout etc, some installations will have good access to the underside of the taps). It will probably be necessary to temporarily put the unit in place so that the length of pipes and the need for bends can be worked out.

When using a solder tap fitting, make the joint to the pipe (remove the fibre washer while you are doing this) before connecting the fitting to the tap.

When using compression tap fittings, it is easier to tighten the joint onto piece of pipe before connecting the fitting to the tap.

To fit tail adaptors:

  • Wind two or three layers of PTFE tape clockwise (when viewed from the end of the tail) around the thread of the tail of the tap.
  • Apply a thin coat of plumbers jointing compound to the thread inside the adaptor.
  • Screw the adaptor onto the tail of the tap and tighten, while holding the body of the tap) using a tap spanner, a 'C' spanner or stilsons.

To connect the tap fitting to the tap (this applies whether or not tail adaptors have been fitted):

  • Wind two or three layers of PTFE tape clockwise (when viewed from the end of the tail) around the thread of the tail of the tap (or tail adaptor). Keep the tape clear of the end of the tail where the fibre washer will sit.
  • Fit the fibre washer over the end of the connector and seat it on the flange around - never reuse fibre washers.
  • Push the end of the connector into the tail of the tap (or adaptor) and tighten the nut onto the tail by hand.
  • Tighten the nut of the connector using a suitable spanner or stilsons - hold the body/spout of the tap so that it cannot turn while the connector is being tightened.