Outdoor Tap Installation in London — Cost, Requirements and What to Expect
An outdoor tap costs £150-300 to install in London and is one of the most requested simple plumbing jobs. This guide covers the installation requirements, water regulations, and what the job involves.
Outdoor Tap Installation — What Is Involved
A standard outdoor tap installation involves:
- Locating the nearest convenient cold water pipe (usually under the kitchen sink or in a utility room near the rear of the property)
- Running a 15mm pipe from that supply through the external wall
- Fitting the outdoor tap body on the external wall
- Installing an isolating valve inside the property (to turn off the outdoor tap without affecting the rest of the supply) and ideally a double-check valve to comply with Water Regulations
- Testing for leaks and insulating any exposed pipework
Cost of Outdoor Tap Installation in London
- Standard installation (through rear wall, kitchen supply): £150-250 including parts
- Longer pipe run (rear garden, tap at far end of garden): £200-400 depending on run length
- Installation in basement property or flat (longer run required): £200-350
Most outdoor tap installations are a half-day job for a plumber. Parts cost £30-60 (tap, fittings, pipe, double check valve, back plate elbow).
Water Regulations Requirements
Under the Water Supply (Water Fittings) Regulations 1999, outdoor taps are classified as a fluid category 3 risk — they can potentially allow non-potable water (garden hose, chemical sprayer) to backflow into the drinking water supply. A double-check valve is therefore required on the supply to the outdoor tap.
A competent plumber will fit a double-check valve as standard. An outdoor tap installation without a double-check valve is technically non-compliant, though Thames Water does not routinely inspect individual installations.
Preventing Frozen Outdoor Taps
In London winters, the exposed pipework leading to an outdoor tap can freeze — particularly if the tap is on an exposed north-facing wall and the pipe runs through an unheated garage or cavity wall space.
Prevention:
- Use the indoor isolating valve to shut off the outdoor tap supply in late autumn
- Open the outdoor tap to drain the remaining water from the exposed section
- Lag any exposed pipework with foam insulation where it exits the heated building envelope
A "frost-proof" or "anti-siphon" outdoor tap body eliminates this maintenance step — these taps automatically drain the exposed portion when turned off. They cost £10-20 more than standard taps and are worth fitting in any London installation.
Frequently asked questions
How much does it cost to fit an outdoor tap in London?
A standard outdoor tap installation through the rear wall of a London terraced house or semi costs £150-250 including parts. Longer runs (far end of garden, side return) cost £200-400. Most plumbers complete this in 2-4 hours.
Do I need planning permission for an outdoor tap in London?
No — fitting an outdoor tap is permitted development and does not require planning permission. It does require compliance with the Water Supply Regulations (double-check valve) but no formal approval process.
Can I fit an outdoor tap myself?
In theory yes — there is no legal requirement for outdoor tap installation to be done by a qualified plumber (unlike gas or electrical work). However, the core drill through the external wall, correct double-check valve fitting, and making a leak-free connection to the supply all benefit from plumbing experience. A poorly made connection behind the wall is expensive to access and fix later.
Will an outdoor tap increase my water bill?
If you are on a water meter (Thames Water meter billing covers most London properties installed after 1990), yes — you pay for the water used through the outdoor tap. A typical summer garden watering use adds £15-40/year. If you are not on a meter (flat-rate billing), water used through the outdoor tap has no direct charge.