Fitting an outside tap

An outside tap, with a hose connector, is virtually essential for the gardener or car owner. It saves connecting a hose pipe to the tap over the kitchen sink, which can involve an inconvenient suspension of other kitchen activities and, by creating back pressure within the tap, may lead to early gland failure – indicated by water round the spindle.

Fitting an outside tap is a job you can easily do yourself, particularly if you use a proprietary garden tap kit – you should be able to obtain one of these from your local builders merchant, DIY stockist or online. Before you begin work you should get in touch with your local water authority to find out whether, and under what conditions, they will permit the connection of an outside tap to the rising main. Normally this will be allowed, but the authority will probably make an extra charge on the water rate for the use of the tap.

Preparing for installation

Drill a 25mm diameter hole through the external wall to within 350mm of the rising main and about 75mm above the level at which the tap will be fitted. You can use a cold chisel and club hammer to make the hole, but an electric drill with a 25mm it will of course make the job easier – particularly if the drill has a hammer action.

Turn off the main stopcock and drain the rising main from the tap over the kitchen sink – if there is a draincock immediately above the stopcock, drain from this as well. Use a hacksaw to cut a 19mm piece out of the rising main at the same distance from the floor as the hole which you have cut through the wall. Make sure your cuts are made squarely and remove any burr from the pipe ends with a file.

Carrying out installation

Unscrew the cap nuts and olives from the two ends of the crosspiece or run off the tee junction supplied with the kit. Smear the pipe ends with boss white and slip first a cap nut and then an olive over one of the cut ends of the pipe. Smear the olive with boss white. The make fitting easier the tee junction has no pipe stop at one end; pull out the pipe end and slip this end of the tee over it. Push the olive up to the tee and loosely screw on the cap nut – don’t tighten it. Fit the cap nut and olive over the other pipe and apply boss white as before, then push the tee up over this pipe end until the pipe end is firmly against the pipe stop. Move the olive up to the tee and screw on the cap nut. Make sure the outlet of the tee is directed, parallel to the wall, towards the hole you have cut in the wall. Hold the body of the tee with an adjustable wrench and tighten the cap nuts with a spanner – this will help prevent overtightening.

Screw-down stopcock

Although not included in the garden tap kit, you should fit a screw-down stopcock into the length of pipe inside the kitchen. During winter this can be turned off and the outside tap opened to preclude any risk of frost damage. Fitting this stopcock will also reduce time the rest of the plumbing system is not in action; once it is in position – and turned off – the main stopcock can be opened so water flows through the rising main and all the domestic plumbing fittings can be brought back into use. This means you can take your time over fitting the outside tap and avoid possible mistakes from trying to get the job done too quickly.

Cut a 200mm length from the 330mm pipe without elbow; fit one end of this into the tee in the rising main using a compression joint (cap nut, olive and boss white) in the same way as for fitting the tee. Attach the free end of the pipe to the inlet side of the stopcock, again using a compression joint. Take the 330mm length of 15mm copper tube with elbow attached and push it through the hole in the wall, from the inside, so the fixed connection of the elbow is inside the wall. Carefully measure the distance between the outlet of the screw-down stopcock and the outside end of this elbow and allow extra length for the pipe which will be within the fittings. Using a hacksaw, cut the remaining piece of copper tube without elbow to the required length and connect the two ends to the elbow and the outlet of the stopcock with compression joints as before.

Finishing off

Outside the house, cut the pipe end so 25mm is projecting from the hole in the wall. Connect the elbow joint to this pipe end so the outlet of the elbow points downwards to the position at which you want to fix the outside tap. Place the wall-plate elbow against the wall, mark the screw positions and drill and plug the wall. Cut the short piece of copper tube to length, if necessary, and connect the outlet of the elbow projecting from the wall to the inlet of the wall-plate. Then screw the wall-plate to the wall. To ensure a watertight joint bind PTFE thread-sealing tape round the tail of the tap and screw the tap into the wall-plate elbow. If, when it is first screwed home, the tap is not upright, add washers to the tail until it comes to the right position. The tap handle will be angled away from the wall so you can turn it without grazing your fingers. Use an exterior grade filler to repair the hole in the wall.


These instructions for fitting an outside tap apply only to houses with a 15mm copper or stainless steel rising main. Some houses, where water pressure is low, may have a 22m rising main and a reducing tee will be needed; this is fitted in the same way as an ordinary tee. Also, in older houses there may be a lead or heavy galvanised steel rising main. To connect an outside tap to main of this kind, you should seek professional help – at least for fitting the tee junction to the rising main.

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