Garden Tap Installation with Hot and Cold Water: Plumbing Options

An outside tap with both hot and cold water is genuinely practical for washing muddy boots, cleaning garden tools, or filling a hot tub — and more achievable than many homeowners assume. A cold-only garden tap is one of the most common small plumbing additions in UK homes, but adding a hot supply outdoors involves connecting to the domestic hot water system, complying with the Water Supply (Water Fittings) Regulations 1999, and usually engaging a qualified plumber. Understanding the options before you plan the project saves both time and money.

Key points

• The Water Supply (Water Fittings) Regulations 1999 require a double check valve (minimum Type EA backflow prevention to BS EN 13959) on every garden tap to prevent contaminated garden water from siphoning back into the mains supply.
• Hot water outdoor taps must be connected to the domestic hot water system — combi boiler, unvented cylinder, or point-of-use heater — which typically requires a WaterSafe-registered plumber.
• All external pipework must be thermally insulated against frost; uninsulated outdoor pipes breach the Water Fittings Regulations and are commonly excluded from home insurance claims.
• A thermostatic mixing valve (TMV) is strongly recommended where the hot supply temperature could exceed 48°C at the outlet, to prevent scalding risk.
• Indicative UK costs, last reviewed 2026-05-04: cold-only tap £150–£350 fitted; hot and cold installation £350–£650+, depending on pipe run length and fittings required.

Options for outdoor hot and cold water

Option 1 — Separate hot and cold taps: Two tap points on an external wall, each fed by its own pipe run from inside the house. Straightforward technically; mirrors standard internal domestic plumbing; requires two separate wall penetrations.

Option 2 — Combined mixer tap: A single outdoor mixer tap fed by separate hot and cold supply pipes, allowing blended temperature at one outlet. Pre-assembled outdoor mixer sets are available from plumbing merchants. Requires careful pipework sizing to avoid pressure imbalance between hot and cold legs.

Option 3 — Cold tap with point-of-use heater: A standard cold garden tap is installed, and hot water is provided by a compact electric point-of-use heater mounted close to the tap. Avoids a long hot pipe run from the main system and is more practical for infrequent outdoor hot water use.

Comparison of garden hot and cold water options

Water regulations you must comply with

The Water Supply (Water Fittings) Regulations 1999 apply in England and Wales. Scotland operates under the Water Byelaws 2004; Northern Ireland under the Water and Sewerage Services (Northern Ireland) Order 2006.

For any garden tap — cold or hot — you must:

1. Fit a double check valve on the supply to the tap. This is a legal requirement, not optional guidance.
2. Insulate all external pipework against frost — a breach of the Regulations and a common insurance exclusion if ignored.
3. Use WRAS-approved fittings listed in the Water Fittings and Materials Directory.
4. Check whether notification to your water supplier is required — a WaterSafe-registered plumber can advise and submit notification where needed.

For hot water connections specifically: fit a TMV where supply temperatures may exceed 48°C, and consider a point-of-use heater for runs longer than approximately 8–10 metres to reduce dead-leg heat loss and water waste before the tap runs hot.

Homeowner checklist: before planning your installation

• Identify the nearest cold supply pipe (usually under the kitchen sink) and the nearest hot pipe (near the airing cupboard or boiler).
  
• Measure the pipe run distance to the desired tap location on the outside wall.
  
• Confirm the wall construction — cavity, solid masonry, or timber frame — as this affects drilling method and insulation approach.
  
• Check whether your hot water system can support an additional draw-off without reducing pressure to existing outlets.
  
• Source WRAS-approved fittings, including a double check valve, before starting or briefing a plumber.
  
• Decide on your approach: separate taps, mixer tap, or cold tap with point-of-use heater.
  
• For hot water: check the temperature output at the cylinder or boiler and decide whether a TMV is needed.
  
• Obtain quotes from at least two WaterSafe-registered plumbers if the work involves the hot water system.
  

Which professional do you need?

• Cold-only garden tap, DIY possible: Achievable for a confident DIYer using WRAS-approved fittings and the required double check valve. Notifiable work is better handled by a WaterSafe-registered plumber.
• Hot and cold supply: Appoint a WaterSafe-registered plumber. Connecting to a pressurised hot water system requires professional competence and ensures the installation is correctly notified.
• Not a gas engineer: A Gas Safe registered engineer is needed only if work involves the boiler itself — the tap pipework connection is a plumbing matter, not a gas safety matter.
• General builder or handyperson: Not appropriate for notifiable plumbing work under the Water Fittings Regulations.

When to get professional help

Engage a WaterSafe-registered plumber when:

• The installation involves any connection to the hot water system.
• The pipe run requires drilling through a cavity wall at or near damp-proof course level.
• You are unsure whether your current water pressure can support an additional outdoor draw-off.
• Your property is on a private water supply or borehole — regulations and backflow risks differ significantly from mains-fed properties.

How Housey can help

Housey connects homeowners with local home improvement professionals across the UK. If you want to compare quotes from WaterSafe-registered plumbers for a hot and cold garden tap installation, use the Housey platform to request and review quotes before committing to a contractor.

Frequently asked questions

Can I install a cold garden tap myself?

Yes, if you are comfortable with compression or push-fit fittings and you fit the legally required double check valve. Many confident DIYers install cold garden taps successfully. For notifiable work under the Water Fittings Regulations, a WaterSafe-registered plumber can handle notification on your behalf and provide a workmanship guarantee, removing the administrative burden from you.

How much does it cost to install a hot and cold garden tap?

Indicative UK costs, last reviewed 2026-05-04. A cold-only tap typically costs £150–£350 fitted. A hot and cold installation is likely to cost £350–£650+, depending on pipe run length, wall type, and whether a thermostatic mixing valve or point-of-use heater is required. Always obtain at least two quotes from WaterSafe-registered plumbers before proceeding.

Does a garden tap need planning permission?

No, planning permission is not required for a standard garden tap installation. If you live in a listed building or conservation area and the pipework would be visible on an external elevation, check with your local planning authority — though in practice a single tap fitting very rarely raises any planning concerns.

What is a double check valve and why is it required?

A double check valve prevents garden water — which may contain fertiliser, pesticides, or animal waste — from siphoning back into the mains supply if pressure drops. Fitting one is a legal requirement under the Water Supply (Water Fittings) Regulations 1999 for any garden tap. WRAS-approved double check valves are available from most plumbing merchants and online suppliers.

Can I connect a garden tap to a combi boiler?

Yes, but a plumber should assess whether your boiler has sufficient capacity for an additional hot draw-off without reducing flow and pressure to existing taps and showers during simultaneous use. For longer pipe runs, a dedicated point-of-use electric water heater mounted close to the tap is often more practical and energy-efficient than a long hot pipework run from the boiler.

Sources and further reading

• Water Supply (Water Fittings) Regulations 1999 — legislation.gov.uk
• WaterSafe: find an approved plumber — WaterSafe
• WRAS Water Fittings and Materials Directory — Water Regulations Advisory Scheme
• Citizens Advice: home repairs and improvements — Citizens Advice