Showers Explained: Electric, Mixer & Power

Choosing the right shower type is less about preference and more about matching the shower to your home’s water system. Install an electric shower on a high-pressure combi boiler and you are throwing away its main advantage; fit a power shower to a gravity-fed system that already delivers good flow and you are wasting electricity on a pump you don’t need. This guide explains how each type works, what it costs, and which is right for your setup.

The Three Main Types of Shower

There are three core shower types sold in UK homes. Understand which water system you have first, then choose the shower type that fits.

Electric Showers

An electric shower heats cold water on demand using an internal element, in the same way a kettle heats water. It is entirely independent of your boiler, if your boiler breaks down, you can still shower.

How they work: Cold mains water passes over a heating element rated between 7.5 kW and 10.8 kW. The higher the kilowatt rating, the more hot water the element can produce at a given flow rate. At 10.8 kW you get a warmer spray at a better flow rate than at 7.5 kW, but you need a sufficiently sized electrical circuit (usually a 45–50 A dedicated supply from the consumer unit).

Pros:

• Works with any water system including gravity-fed and combi boilers
• Hot water on demand, no waiting for the cylinder to heat up
• Only heats water being used, so there is no standing heat loss
• Easy to install in most situations where a cold mains supply is accessible

Cons:

• Flow rate is limited by the element size, can feel weaker than a mixer on a good boiler
• Running costs can be higher than a gas-heated mixer shower over time
• Requires a dedicated electrical circuit; older properties may need a consumer unit upgrade

Installation cost: £250–£600 all-in, including the unit, an electrician to run the circuit, and a plumber to connect the water supply. If a new circuit is needed from the consumer unit, add £150–£300.¹

Best for: homes with gravity-fed systems where mains cold pressure is good but hot supply is limited; properties where someone needs a shower regardless of boiler status; rental properties where simplicity is valued.

Mixer Showers

A mixer shower blends hot and cold water from your existing supplies before it reaches the showerhead. It does not heat water itself, it relies entirely on your boiler or hot water cylinder.

Manual mixers use a single lever or two separate controls to blend hot and cold. They are inexpensive but provide no protection against temperature fluctuations when someone flushes a toilet or runs a cold tap elsewhere in the house.

Thermostatic mixers incorporate a thermostatic cartridge that maintains a set temperature automatically. They are the standard choice for new installations and cost more but offer genuine comfort and safety, particularly important where children or elderly people use the shower.

Pros:

• Consistent temperature (thermostatic models)
• Can deliver high flow rates if your water pressure supports it
• Wide design choice from budget to premium
• Lower running costs than electric showers when heated by a gas boiler

Cons:

• Dependent on your boiler working and your hot water cylinder being full (if you have a stored-water system)
• Performance is limited by your home’s water pressure, low pressure produces a disappointing spray
• Thermostatic cartridges eventually need replacing (typically every 5–10 years, £30–£80 for the part)

Installation cost: £300–£800 all-in for a thermostatic mixer with a riser rail and handset, assuming existing hot and cold supplies are nearby. A concealed (recessed) thermostatic valve with overhead drencher will push this to £600–£1,500 depending on tiling works needed.

Best for: combi boiler homes with good mains pressure; anyone wanting the best shower experience and flow rate; new bathroom builds where pipework can be planned in.

Power Showers

A power shower is essentially a mixer shower with a built-in electric pump. The pump boosts the flow rate from a gravity-fed hot water cylinder. If you have a combi boiler (which already delivers mains pressure), a power shower offers no benefit, the pump has nothing to boost and can actually cause problems.

How they work: Hot and cold water are blended in the usual way, then the pump increases the flow before it reaches the showerhead. Pumps are typically rated at 1.5–3 bar boost pressure. The pump is powered by a normal 13 A socket (though ideally a fused spur).

Pros:

• Transforms a weak gravity-fed shower into a high-flow experience
• Good retrofit option for older properties with vented hot water cylinders

Cons:

• Only suitable for gravity-fed / vented cylinder systems, never fit with a combi boiler
• Uses significantly more water and hot water than a mixer shower, can drain a 120-litre cylinder quickly
• Higher running costs due to pump motor electricity consumption
• Bulkier units than standard mixer showers

Installation cost: £350–£800 all-in including unit, plumbing connection, and electrical spur. The hot water cylinder must be in good condition; a corroded cylinder may need replacing at the same time (£600–£1,200 for a new vented copper cylinder).

Best for: gravity-fed systems in older UK homes where the hot water pressure is poor; anyone who wants more flow without replacing their entire heating setup.

Digital and Smart Showers

Digital showers use a remotely located thermostatic valve (often hidden under the bath or in a cupboard) controlled by a wall-mounted digital pad. They offer precise temperature setting, pause function, and in some cases app control. They suit both combi and stored-water systems.

Expect to pay £700–£2,500+ for the valve and controls, plus plumbing and electrical installation. The main appeal is the clean, minimal aesthetic of the wall pad and the ability to pre-heat the shower before you get in.

Which Shower Type for Which Boiler?

Key Regulations and Safety Points

All shower electrics must comply with Part P of the Building Regulations (Approved Document P). Work in a bathroom zone requires a qualified electrician or must be notified to your local authority building control. A shower pull cord isolator switch is required to meet the zone regulations, a standard wall switch is not permitted in a bathroom.²

Water regulations (WRAS) apply to all plumbing connections. Any shower fitted to a combi boiler should have a thermostatic cartridge or a separate thermostatic bar valve, Building Regulations Approved Document G requires water at the point of use to be limited to 48°C for baths and showers serving dwellings (with some exceptions for certain adult applications).

What to Budget Overall

For any shower installation involving electrical work, always use an electrician registered with a competent person scheme, or ensure a building regulations notification is made. Plumbing connections in isolation can be done by a competent DIYer, but water supply to a shower should be checked for adequate flow rate (minimum 8 litres per minute for most mixer showers) before purchasing.

The rules in this note are those that apply in England. Scotland, Wales and Northern Ireland have their own building standards and permitted development rights.