Fitting an outside tap

Summary: Learn how to fit an outside tap, install a branch pipe, extend the branch outside and attach a tap.

Before commencing work you must notify your water company, as the installation of an outdoor tap will result in an increase in your water rates. A double check-valve must be fitted as close to the tap as possible to prevent the risk of back-siphonage. If the tap will be fitted close to any outside wall ensure the tap has an angled head to prevent grazed knuckles whenever you turn it on and off.

This project looks at installing an outdoor tap using a copper pipe running off a 15mm (3/5in) rising main, which enters the house through the kitchen and connects to the kitchen taps.

It is advisable to fit a stop tap to the branch pipe running from the rising main, in order to turn off the water and drain the branch pipe for the winter. This will also allow you to complete the installation in two phases.

Measuring out

  • Position the tap on the outside wall of the kitchen, close to the rising main and at least 250mm (10in) above the damp-proof course. Also ensure you can place a bucket under the tap.
  • Mark the tap position on the wall
  • About 150mm (6in) above the tap make another mark indicating the position for the hole.
  • Measure the distance between the position of the hole and a window or other feature and transfer this measurement onto the inside wall. Check that the position of the hole, through which you will feed the branch pipe, is above the main stop-tap on the rising main and that the branch pipe will not be in the way of any other fittings. When satisfied with the position of the hole, mark it with a ‘cross’ on the wall.

Installing the branch pipe

  • Drill holes through the side of the unit accommodating the sink to allow the appliance’s hoses to feed through and connect to the pipes.
  • Turn off the hot and cold water supply to the kitchen.
  • You need to fit Tee valves into the supply pipes at a suitable height for connecting to the appliance. Make two marks 20mm (4/5 in) apart on the cold water supply pipe. Repeat this process on the hot water supply pipe.
  • Then using a pipe slice or hacksaw cut squarely through the pipes. It is best to cut at the lower mark first. When the sections of pipes have been removed file the end of the pipes smooth.
  • Slip the capnuts and olives of the T-valves onto the pipes. To prevent the capnuts and olives slipping off the upper lengths of pipe, attach a spring-clip clothes peg to the pipes.
  • Insert the Tee valve into each of the cut out sections. Using a spanner or wrench tighten the collars which grip the olives, but do not over-tighten.
  • Once the Tee valves are connected to both ends of the supply pipes, a small length of pipe can be fitted to the remaining Tee valve opening, which in turn will be connected to a check valve.
  • Valves with colour-coded taps for hot and cold supply pipes can now be fitted into the check valves. The colour-coded taps should point towards the appliance.
  • Feed the washing machine’s hoses through the holes you have made in the side of sink unit and, after checking the black rubber washer is inside the plastic nut of the hose, screw them onto the appropriate valves.
  • The other ends of the hoses can now be attached to the appliance. Turn on the water and check for leaks.

Extending the branch outside

Beginning with a slim masonry bit, drill through the wall from the inside at the point you marked earlier.
  • Drill through the wall from the inside at the point you marked earlier. Use a heavy-duty power drill (these can be hired) with a masonry bit at least 325mm (13in) long. You may want to use a very slim masonry bit to begin to allow you to drill through the wall much quicker. 
  • Then drill through the hole again with a masonry bit with a diameter slightly larger than that of the pipe (at least 20mm 4/5in). Drill from both sides of the wall. Remove the bit from the hole regularly to clear debris and to let the bit cool.
  • Once the hole is drilled, cut a section of pipe to fit between the double check valve and the hole, allowing enough pipe to fit into the valve at one end and an elbow joint at the other.
  • Then cut another length of pipe to fit through the hole, leaving about 50mm (2in) excess on either end to fit into joints.
  • Using an elbow joint connect the two lengths of pipe and then slide the pipe through the hole in the wall.
  • Connect the other end to the double check valve.
  • From outside, cut down the pipe protruding from the hole to leave only 25mm (1in) projecting from the hole in the wall.
  • Connect another elbow joint to the end of pipe projecting from the wall. The free end of the elbow joint should be pointing down towards the position of the tap.
  • Cut a length of pipe to reach between the elbow joint and the position of the tap.
  • Fit one end of this length of pipe into the inlet of the wall-plate elbow joint.
  • Temporarily fit the other end of the pipe into the elbow joint connected to the pipe projecting from the wall. Holding the wall-plate firmly against the wall, mark the position of the screw holes.
  • Remove the pipe and wall-plate to drill and plug the holes.
  • Reconnect the pipe to the elbow joint projecting from the wall and screw the wall-plate elbow to the wall.
Screw the tap tail into the elbow join.

Attaching the tap

  • Wind some PTFE tape around the tail of the tap.
  • Screw the tap tail into the elbow joint.
  • If the tap spout is not pointing straight downwards when fully tightened, remove it and place thin fibre washers over the tap thread before re-tightening.
  • Turn on the new stop-tap you fitted to the branch pipeand check for leaks.
  • Seal around the pipe hole in the wall with an expanding foam filler, sealant or exterior filler.

Tools needed

  • Spirit level
  • Hacksaw or pipe slice
  • File
  • Adjustable spanner
  • Power drill
  • Masonry bit
  • Screwdriver

Materials needed

  • Tap fitting
  • Copper pipe
  • Tee valve
  • Capnut
  • Olive
  • Foam-filler, sealant
  • Wall filler
  • Elbow joint
  • Wall-plate elbow joint
  • Wall plugs
  • Screws
  • PTFE tape
  • Foam filler, sealant OR wall filler

Related projects

Related cost guides