Installing an outdoor tap: drilling the wall and connecting to the water supply

An outdoor tap changes your life: watering the garden, washing the car or cleaning the terrace without dragging a long hose through the house. Its installation requires drilling a wall and connecting onto an existing water supply, often in the cellar, garage or toilet. It is a plumbing job within reach of a careful DIYer, provided you respect a few golden rules: turn off the water, drill cleanly and check the watertightness. Allow one day and a budget of 30 to 100 euros for the tap, the tee, the valve and the fittings.

Choosing your outdoor tap

• The standard draw-off tap: simple, with a 1/2 or 3/4 inch thread, for occasional use
• The frost-proof tap: fitted with a cap that shuts off the water inside the wall, to be preferred in cold regions
• The wall tap with integrated stop valve, more practical for maintenance
• The quick-connect or standard screw-thread outlet, depending on your garden hose
• The model with an integrated strainer, which protects the thread from impurities

The frost-proof tap is a particularly wise choice if the drilled wall exposes the tap to frost: its system shuts off the water in the warm part of the wall when you close it, avoiding the tap body bursting from the cold. If your region freezes regularly, go for this model or install an indoor stop valve and drain the pipe before winter. The standard 1/2 inch thread suits most garden hoses: however, check the thread pitch of your connector to avoid surprises at the first connection.

The necessary tools

• Hammer drill, masonry bit or wall bit of suitable diameter, possibly a finer bit first
• Hammer, cold chisel and wire stripper if necessary
• Tee fitting, stop valve and fittings suited to your pipework
• PTFE tape or joint paste for the threads
• Spirit level, pencil, tape measure and open-end wrenches
• Bucket, rags and silicone for the watertightness of the wall passage

Drilling the wall cleanly

1. Choose the location: at a comfortable height (about 50 to 80 cm from the floor) and away from walkways.
2. Check on each side of the wall that no cable, pipe or conduit is at the drilling location.
3. Mark the centre of the future hole and drill with a fine bit then at the final diameter, with a slight slope towards the outside.
4. Pass the tap or its extension through the hole, orienting the threaded part towards the inside.
5. Level the tap and fill the space around the tube with silicone or expanding foam.

Connecting onto the water supply

1. Turn off the house's main water supply and open a tap to drain the pipes.
2. Locate a connection point on the existing pipework, preferably after the meter and the main valve.
3. Fit a tee junction onto the pipe, choosing one the same diameter as your pipework.
4. Install a dedicated stop valve between the tee and the outdoor tap, so you can isolate this circuit.
5. Connect the extension or the tap to the thread, wrapping PTFE tape in the direction of the threads.
6. Open the main valve slowly and check the watertightness of all the joints.
7. Let the water run for a few minutes and inspect each fitting with a dry cloth.

Checking the watertightness

Watertightness is checked in both directions: inside and outside. Inside, open the main valve slowly and examine the tee, the stop valve and the threads; a bead of water means the PTFE tape is insufficient or badly applied. Outside, open the tap and check the thread on the hose side, as well as the perimeter of the wall passage, which must stay dry. If a leak appears, turn off the water, dismantle the fitting and redo the sealing with fresh tape. Never leave a leak in place: even a slight one worsens over time.

The mistakes to avoid

• Forgetting to turn off the main water supply before working on the pipework, a cause of water damage
• Drilling in an area where a cable or pipe passes, for lack of prior checking
• Fitting a tee onto a pressurised pipe without an upstream isolation valve
• Using too much PTFE tape, which prevents the threads from tightening fully
• Choosing a tap without frost protection in a region where freezing is common

Installing an outdoor tap is a concrete job that above all demands rigour at the connection and watertightness stage. Whether your pipework is copper, PEX or steel, the principle stays the same: turn off the water, fit a tee, add a stop valve and connect the tap. If you have never soldered copper or if your pipes are old and hard to reach, call in a plumber: a leak behind a wall or in a cellar can cause serious damage. In the case of a simple installation, a dedicated DIYer will finish the job in one day and enjoy a practical outdoor tap all year round.