Bidets and shower toilets in UK homes: water supply, backflow and electrics

Bidets and shower toilets are becoming more common in UK bathrooms. There are several different kinds, and they connect to the water supply in different ways. What they share is that they put a water outlet very close to a toilet. That makes backflow protection the main plumbing question. This guide explains the types, what the water rules say in plain terms, and where an electrician and the water company come in.

The main types

Traditional bidet. A separate low basin next to the WC, with its own tap. Some have a tap that fills the bowl from above the rim. Others have an ascending spray that comes up from inside the bowl.

Bidet spray or douche shower. A small handheld spray on a hose next to the toilet, fed from a valve on the wall. Common in many countries and increasingly fitted in the UK.

Bidet seat. A replacement toilet seat with a built-in washing nozzle. Some are non-electric and use cold water only. Others have a heater, a dryer and a remote control and need power.

Shower toilet (wash-and-dry WC). A complete toilet with the washing, warm water, drying and often a heated seat built in. These are electrical appliances as well as toilets.

The water connection

Each type needs a water supply:

• a traditional bidet usually has hot and cold supplies to its tap, much like a basin;
• a bidet spray usually has a wall valve, which may mix hot and cold;
• non-electric bidet seats often take cold water from the toilet's own supply through a tee;
• electric seats and shower toilets usually take cold water and heat it inside the unit.

Every supply should have its own isolation valve that you can reach, so the appliance can be shut off for repairs without turning off the whole house. See isolation valves.

Where hot and cold are mixed, the temperature matters. A user may not be able to react quickly to water that is too hot. A thermostatic valve can limit the outlet temperature. Our guide to thermostatic mixing valves explains how they work.

Backflow: why these are treated as high risk

If the supply pressure drops, water can be drawn backwards. A spray or nozzle in or near a toilet bowl could then pull contaminated water back into the pipes that feed drinking water taps. That is why the water fittings regulations take these appliances seriously.

Water Regs UK publishes two short checklists on this. Its combined WC bidet checklist says "a combined WC bidet is considered to be a fluid category 5 risk". Category 5 is the highest risk level. It says the unit must either incorporate, or be supplied through, fluid category 5 backflow protection. It also says some combined WC bidets are known to have that protection built in, but where they do, "it is essential to confirm it meets the relevant requirements". Without acceptable built-in protection, the supply needs a suitable category 5 arrangement, for example a break tank with a Type AB air gap.

Its bidet shower checklist says a shower bidet next to a WC is also "a fluid category 5 risk". It says both the cold supply and, where appropriate, the hot supply must go through suitable category 5 backflow prevention. Its diagram marks single check valves on their own as not acceptable.

In practice, this means:

• a cheap bidet spray kit or seat that simply tees into the toilet supply may not meet the regulations on its own;
• a shower toilet or seat that claims built-in protection still needs checking against the requirements;
• the arrangement should be designed by someone who knows the water regulations.

The water fittings regulations apply in England and Wales. Scotland and Northern Ireland have their own byelaws and regulations.

Notifying the water company

Both Water Regs UK checklists say these installations are notifiable in Scotland and Northern Ireland and could be notifiable in England and Wales, for example as a material change of use. They describe the water company's notification check as "important simple and essential". They also say that where notification is not required, for example because an approved contractor does the work, the owner or occupier is still legally responsible for making sure the plumbing complies.

So before fitting one, ask your water supplier or use a plumber who is a member of an approved contractor scheme. Our guide to hiring a plumber explains how to find one.

Electric shower toilets and seats

A shower toilet or electric bidet seat needs a power supply close to the toilet, in a bathroom. That is electrical work for a qualified electrician. Bathrooms have special location rules for electrics, and in England Part P of the Building Regulations applies. Read the Approved Document P page on GOV.UK for the official position, and ask your electrician what applies. We do not give wiring instructions.

Plan the power and water positions before tiling. The maker's installation guide will show where they need to be. The bathroom refit order guide covers getting the trades in the right sequence.

Fitting and living with one

• Replacing an ordinary WC with a shower toilet still involves the usual waste connection. See WC pan connectors.
• The flushing side works like any other toilet. A running toilet or a slow-filling cistern is covered in our toilet fill and flush valves guide.
• Clean the nozzle and descale as the maker says, especially in hard water areas.
• If water leaks from the unit, turn off its isolation valve and switch it off at the power supply before calling the installer.

Product at Wickes

We haven't tested this. It is an example, with what the retailer's page says.

We haven't tested this. Figures are as the maker states them (checked 13 November 2026).

Can I fit a bidet spray to my existing toilet supply?

Not simply by teeing it in. Water Regs UK treats a bidet shower next to a WC as a fluid category 5 risk, which needs a high level of backflow protection. Ask your water supplier or a plumber who knows the water regulations before fitting one.

Does a shower toilet need an electrician?

Yes, if it has a heater, dryer, heated seat or electronic controls. The power supply in a bathroom is work for a qualified electrician, and Part P applies in England.

Do I need to tell the water company about a bidet?

It may be notifiable. Water Regs UK says combined WC bidets and bidet showers are notifiable in Scotland and Northern Ireland and could be notifiable in England and Wales. Check with your water supplier before work starts.