Outdoor Tap Installation CR7

Why install an outdoor tap

An outdoor tap transforms how you maintain your garden and outdoor space. Garden watering with a hosepipe is faster and more water-efficient than carrying watering cans. Car washing, cleaning the patio, filling paddling pools, and topping up water features and ponds all become straightforward with a permanently installed outdoor tap. For London households with small gardens and limited access to outdoor water, an outdoor tap is one of the most practical plumbing additions available.

How the supply is connected

An outdoor tap is typically teed off the kitchen cold supply pipe using a 15mm saddle tee or an inline tee fitting. A 15mm branch pipe is run from the tee to the external wall, where a core-drilled hole (typically 20mm to 22mm diameter) is made through the masonry. The pipe exits the wall and connects to a wall plate elbow — a fitting that holds the tap body against the exterior wall and provides the connection for the tap thread. A standard bib tap (the traditional quarter-turn or capstan-head type) or a modern ball valve body is fitted to the wall plate elbow.

Indoor isolation valve — essential

Every outdoor tap installation must include an indoor isolation valve fitted on the supply branch inside the property. This valve serves two purposes. First, it allows the outdoor tap to be isolated in winter — you turn off the isolation valve, open the outdoor tap to drain any water from the external pipework, and close the outdoor tap. This prevents freezing of the external section of pipe during cold spells. Second, it provides a means to isolate the tap for maintenance without turning off the water supply to the whole house.

Frost protection

The simplest frost protection method is to turn off the indoor isolation valve at the end of autumn and leave the outdoor tap open so the external section of pipe drains by gravity. For properties where this is inconvenient — or where the external pipe run is long and cannot drain fully — a self-draining (frost-protected) outdoor tap is the best solution. When the self-draining tap is turned off, a small internal valve automatically drains the external section of pipe. These taps cost a little more but eliminate the need to remember to isolate the supply each winter.

Double check valve — a legal requirement

The Water Regulations Advisory Scheme (WRAS) requires a double check valve to be fitted on every outdoor tap supply. The requirement exists to prevent backflow — if a hosepipe is left submerged in a garden pool, a paddling pool, or a bucket of soapy water, and mains pressure drops suddenly (for example, during a main burst nearby), water could siphon back from the hosepipe into the mains supply, potentially contaminating the drinking water supply. A double check valve (also called a non-return valve) contains two spring-loaded check valves in series that prevent any backflow. WRAS-approved double check valves are fitted on every outdoor tap installation by Prestige Engineers as standard.

Outdoor taps in London flats and terraces

Many London flats do not have a suitable external wall for a traditional outdoor tap installation. Purpose-built flats often have no direct access from the kitchen to an external wall — the kitchen internal wall may face a communal corridor rather than the outside of the building. Terraced houses in London typically have a rear access route from the kitchen to the back garden, making outdoor tap installation straightforward in most cases.

Roof terrace and balcony taps can be installed in flats where a water supply pipe can be routed to the terrace or balcony location. We survey the property before confirming whether installation is feasible and quote accordingly. In some flat configurations, the pipe route may need to run through a cupboard or service void to reach the external point.

No Building Regulations notification required

A standard outdoor tap installation involves only plumbing work — tapping off the existing cold water supply, running a branch pipe, core-drilling through the wall, and fitting the tap body. There is no electrical work involved, so Part P of the Building Regulations does not apply. No Building Regulations notification or permission is required for a simple outdoor tap installation. The work is subject to the Water Regulations (the requirement for a double check valve and an indoor isolation valve), which we satisfy as a standard part of every installation.