Outdoor showers in the UK: supply, drainage, backflow and frost

An outdoor shower is handy for rinsing off after the beach, before a hot tub or paddling pool, or after muddy garden jobs. The simplest kind is a cold shower head on a post, fed from a hose. Fixed and heated showers are another matter. Each one brings questions about backflow, drainage and frost, and a heated one adds electrical work and possibly gas.

Types of outdoor shower

Hose-fed cold shower. A freestanding post or a wall-mounted head that connects to a garden hose. It needs no fixed plumbing and is put away in winter.

Fixed cold shower. A shower head and valve fixed to a wall or post, with its own pipe from the cold supply. This is plumbing work.

Solar or "sun-warmed" shower. A post or bag with a dark tank that warms the water in the sun. It is fed from a hose. The water is only as warm as the weather allows.

Hot and cold mixer outdoors. A fixed mixer fed with hot water from the house. This needs a hot pipe run outside, a mixing valve and good protection from frost.

Electric or gas-heated outdoor shower. These are not DIY. See below.

The supply

Most simple outdoor showers are fed from an outside tap. The tap must be properly protected against backflow. See our guide to outdoor taps for the backflow and frost rules for garden taps.

A fixed shower with its own cold pipe should have:

• a separate isolating valve inside the house, so you can shut it off and drain the outside section in winter (see isolation valves);
• suitable backflow protection (below);
• pipework that is supported, protected and, where it runs through cold spaces, insulated (see pipe lagging).

Hot water outside adds a scalding risk as well as a frost one. A thermostatic mixing valve can limit the outlet temperature. See thermostatic mixing valves.

Backflow: why the setting matters

Any shower outdoors can let dirty water get back into the supply if the pressure drops: a shower head dropped into a paddling pool, a hose left in a pond, or a spray lying in a puddle. The Water Supply (Water Fittings) Regulations 1999 apply in England and Wales and require suitable backflow protection. Scotland and Northern Ireland have their own rules.

Water Regs UK's page on hose union taps says hoses used solely for watering a domestic garden or washing personal vehicles are typically a fluid category 3 risk. Its list of higher-risk activities includes hose use for "refilling and areas adjacent to ponds, swimming pools, spa baths or hot tubs". It says hose union taps used in those circumstances are classed as fluid category 5 risks "unless an assessment by the local water undertaker determines otherwise". A shower next to a pool or hot tub is exactly that kind of setting.

In practice, this means a pool-side or hot tub shower may need a higher level of backflow protection than an ordinary garden tap. The local water company decides case by case. Ask your water supplier or a plumber who knows the water regulations before you fix anything permanently. Some new fixed water fittings have to be notified to the water company before work starts.

Drainage

Shower water has to go somewhere. For a hose-fed shower used now and then, a gravel area or a well-drained lawn may be enough. For anything used a lot, think about:

• where the water runs. Do not let it soak against the house walls or run onto a neighbour's land;
• soap and shampoo. Water with soap in it should not go into a surface water drain that runs to a stream or soakaway meant only for rainwater. Ask a plumber how your drains are arranged;
• a fixed tray and waste, connected to the foul drain. That is drainage work, and Part H of the Building Regulations applies in England.

Our guide to outside drains explains the difference between foul and surface water drains.

Frost and winter

Water left in an outdoor shower freezes. In winter:

1. Disconnect hose-fed showers and store them indoors.
2. For fixed showers, close the indoor isolating valve and open the shower valve to let the outside section drain.
3. Leave the valve open, or as the maker's instructions say, so trapped water can escape.
4. Check for splits and leaks in spring before relying on it again.

A mixer or thermostatic valve outdoors is especially vulnerable. Many are not designed to survive freezing with water inside.

Heated and electric outdoor showers

An electric shower outdoors, or a heater feeding an outdoor shower, brings water and electricity together in an exposed place. That is electrical work for a qualified electrician. It involves special location rules, and in England Part P of the Building Regulations applies. See electric vs mixer showers for how electric showers differ from mixers. We do not give wiring instructions.

Do not use a gas-fired water heater or portable gas heater for an outdoor shower without a Gas Safe registered engineer confirming that it, its location and its ventilation are safe. Gas appliances are not DIY. See when to call a Gas Safe engineer.

Saving water

An outdoor shower can use a lot of water, especially if it is left running. A water butt cannot safely feed a shower, because stored rainwater is not drinking quality. Our guide to water butts and garden watering covers using rainwater in the garden instead.

Can I connect an outdoor shower to my garden tap?

For an occasional hose-fed shower, many people do. The tap must have suitable backflow protection. A pool-side or hot tub shower may need more. Check with your water supplier or a plumber who knows the water regulations.

Do I need a drain for an outdoor shower?

Not always for a small, occasional cold rinse onto gravel. A shower that is used a lot, or that drains soapy water, should be properly drained. Ask a plumber or building control about connecting it to the foul drain.

Can I fit an electric shower outside?

Not as DIY. It needs a qualified electrician, and it must be suitable for an outdoor location. Part P applies in England.