How to fit an outside tap


Putting in an outside tap is often considered more trouble than it’s worth and as our winters get colder many would rather put up with the inconvenience of using internal hose connectors and connecting to the kitchen sink rather than risk frozen pipe work. 

Before you start there are a few tools you might need. I have put a list together for you. 

Pliers , power drill , outside tap kit , bucket , ptfe tape , pipe cutters , adjustable spanner , small and large drill bits , plugs and screws. 

1: First of all you will need to know how to turn off the water supply. Try and locate your main stop tap. This is normally under the kitchen sink or wherever the mains supply enters the property. 

If you cannot find the stopcock, you may be able to turn off the water at the main stop tap outside in the path the water authority’s valve . You’ll need a special long-handled spanner, available from plumbers’ merchants. 

Once the water supply is turned off, open the cold tap on your sink until the water stops running. It is also a good idea to go upstairs and open the cold tap up there as well. 

2: Get out the outside tap kit and see what size you need the hole to be. then get a drill bit out about 2mm bigger and fix it into your drill. Then drill a hole through your external wall. 

Please be careful when drilling. the hole should be at least 400mm from the floor and at least 300mm above the damp proof course. 

When drilling, make sure the hole is wide enough to take the 15mm size of the pipe’. 

Steadily drill through the wall with a heavy duty power drill and a large masonry bit at least 330mm long. 

Remove the drill bit regularly to clear the loosened masonry. 

then mark the wall for where the holes need to be to fix the outside tap. 

3: Pipe work for the outdoor tap 

making sure the water supply is turned off, cut through the cold water pipe directly above the exit hole you have drilled in the wall. Use a hacksaw or pipe cutter to do this and file the ends of the pipes smooth. 

Remove enough pipe to fit a 15mm T connector. 

Connect one end of a short bit of pipe to the T-piece and the other end to an Isolation Valve so that the water supply to the new tap may be turned off when required in the future . 


Isolation Valves allow you to turn the water off to an individual appliance without having to turn off the whole water supply. 

Make sure you fit the valve the correct way around otherwise it won’t work correctly. There is an arrow on the valve indicating the direction of the flow of water. 

There are two types: a ‘Push-fit’, which simply pushes into the ends of the pipes, and a ‘Compression’  which we show how to fit here. 

Having turned off the water supply, mark the section of pipe that needs removing to receive the valve. 

Cut the section from the pipe with either a pipe slice or hack saw and file the ends of the pipes smooth. 

Now slide a compression nut onto each piece of pipe followed by the olives . 

Push each end of the pipe into the fitting and tighten the compression nuts by hand. 

Use a pair of pliers to hold the body of the valve and tighten the compression nuts about 3/4 of a turn. 

When you turn on the water supply once more, check for leaks – if necessary tighten the compression nuts a little further. 

Next you need another short piece of pipe which connects the Isolation Valve to a Double Check Valve. 


Water regulations specify that you must fit a Double Check Valve to your outside tap pipe work. 

Double Check Valves stop water flowing back up a pipe the wrong way. This prevents contaminated water entering the drinking water supply in your home. 

For a new external tap the valve must be fitted in your internal pipe work, after the Isolation Valve. 

Double Check Valves are fitted in a similar way to Isolation Valves – see ‘Fitting an Isolation Valve’ above. 

If you have an existing external tap you may replace it with a tap that already incorporates a Double Check Valve. 

After fitting the Double Check Valve insert another short piece of pipe and an elbow (. Then fit a length of pipe long enough to reach horizontally through the wall to the outside. When through the wall, cut the pipe to leave about 25mm protruding. 

Finally you will need to cut a piece of pipe that reaches from the horizontal pipe protruding from your outside wall down to the position of your tap. 

These pipes are connected using another elbow joint. 

Connect all the parts together and tighten the joints with two adjustable spanners. If any joints leak when the water supply is turned back on they can be tightened further, but do not over-tighten. 

4: Attaching the new outdoor tap 

Drill the fixings holes for the tap’s wall plate, insert plugs and screw the tap plate to the wall. Screw the tap tail into the elbow join. 

Use plastic retaining clips for the pipes on the inside wall to stop the pipes vibrating and knocking against the wall. 

Seal around the pipe hole in the wall with an expanding foam filler or sealant. 

Finally, turn the water supply back on and check for any leaks. 

Tighten any joints as necessary and then you’re ready to go.

Edinburgh Central Heating Services offer free estimates and range of skills. A 24-hour emergency plumbing service is also offered. For more information visit or telephone 0131 5102418