Electric vs mixer vs thermostatic showers
The first decision when you buy a new shower isn’t which brand or which look. It’s which type. The three you’ll see most often electric, mixer and thermostatic heat the water in different ways, suit different water systems, and offer different levels of safety. Get the type right and the rest of the choice opens up. Get it wrong and your new shower won’t work the way it should, even when the model is excellent.
This guide explains how each type works, where each one belongs, and the honest pros and cons of all three, so you can pick the type that suits your home before you fall for a particular model.
The three types at a glance
The short version, before the detail:
| Type | How it heats water | Best for |
|---|---|---|
| Electric | Heats cold mains water inside the unit, on demand | Any home with a cold mains supply; doesn’t need a working boiler |
| Mixer | Mixes pre-heated hot and cold water from your existing plumbing | Homes with a reliable hot-water supply (combi, unvented or pumped gravity) |
| Thermostatic | A mixer with a built-in valve that holds the temperature steady | Any home using a mixer where safety and a consistent temperature matter |
Thermostatic isn’t really a fourth category alongside electric and mixer; it’s a safety feature added to a mixer shower. So the genuine choice is electric versus mixer, with thermostatic the upgrade most modern mixers now have as standard.
How each one works
Electric showers
An electric shower takes cold water straight from your mains and heats it inside the unit using a built-in heating element, the same way a kettle does. It doesn’t draw on your boiler or hot-water tank at all; it just needs a cold-water supply and a dedicated electrical connection. The temperature is set by how fast the water flows past the element — slower flow gets hotter, faster flow gets cooler.
Because it heats on demand, an electric shower works in homes where the hot-water system can’t keep up, or where you don’t want the shower competing with the kitchen tap or the dishwasher for hot water. It also keeps working when the boiler doesn’t.
Mixer showers
A mixer shower does what the name suggests: it mixes hot and cold water from your existing plumbing to give you the temperature you want at the showerhead. The hot water has already been heated by your boiler or stored in a cylinder, so the shower itself contains no heating element. It’s simpler internally, and the flow rate is usually better than an electric shower because nothing is restricting it to heat the water.
The catch is that a mixer is only as good as the hot water it’s mixing. If your boiler can’t keep up with demand, or your hot water runs out, the shower notices straight away. On the other hand, if you’ve got plenty of hot water at decent pressure, a mixer gives you the most powerful and natural-feeling shower of the three types.
Thermostatic showers
A thermostatic shower is a mixer with an extra safety valve. The valve constantly monitors the temperature of the water coming out and adjusts the mix to keep it steady. If your cold supply suddenly drops (someone flushes a toilet or runs a tap), the valve cuts back the hot water at the same rate, so the shower doesn’t scald. If the hot supply fails entirely, most thermostatic showers will shut off rather than send icy water at you.
It’s the safest type to buy and the most common in newer bathrooms. The temperature stability matters most in homes with children, older users, or households where the plumbing is busy enough that pressure changes happen regularly.
Pros and cons
Each type has clear strengths and honest trade-offs. Worth knowing both before you commit.
- Electric: works in any home with cold mains, independent of your boiler, hot water never runs out. But flow rate is lower than a good mixer, the unit is visible on the wall, and the heating element will eventually need replacing.
- Mixer (non-thermostatic): strong flow, simple internals, often the cheapest option per unit. But the temperature can swing if your hot or cold supply changes, and it depends on your boiler or cylinder.
- Thermostatic mixer: all the benefits of a mixer plus safe, stable temperature. The slightly higher cost is usually worth it, and it’s now standard on most modern bathrooms.
Running costs
It’s a fair question that the brochures rarely answer cleanly. The honest read is that mixer and thermostatic showers are usually cheaper to run than electric ones, because they piggy-back on whichever fuel heats your home’s water (usually gas on a combi or system boiler), and gas is typically cheaper per unit of heat than electricity. An electric shower heats every drop of water using electricity directly, which is convenient but costlier per shower.
The numbers swing with your tariffs and how efficient your boiler is. On a modern condensing combi running on mains gas, a ten-minute mixer shower will usually cost less than the same shower from an electric unit. On an old, inefficient gas boiler, the gap narrows. On all-electric homes (or homes considering moving away from gas), an electric shower no longer looks any pricier than the alternatives. The point isn’t to scare you off any one type, but to know what you’re committing to over the next several years.
Three things help on running costs whichever type you pick: a flow restrictor or eco-flow head saves real money over a year of daily showers; a shorter shower habit obviously saves more; and a properly-fitted thermostatic mixer wastes less water than a non-thermostatic one because you spend less time fiddling with the temperature.
Which suits your water system?
Compatibility is where most wrong-shower decisions happen. The short version, by system type:
- Combi boiler: mixer or thermostatic. The combi heats water on demand at mains pressure, which is exactly what a mixer needs. An electric shower works too if you want a second shower independent of the boiler.
- Unvented mains-pressure system (cylinder fed by mains): mixer or thermostatic, ideally thermostatic. You’ve got plenty of pressure and stored hot water, which suits a powerful mixer.
- Gravity-fed system (cold tank in the loft, hot cylinder): typically lower pressure. A mixer can work, but you may need a shower pump or a power shower (a mixer with a built-in pump) for a decent flow. Or fit an electric shower, which doesn’t care about your hot-water pressure.
- Low water pressure generally: an electric shower (heats the mains itself) or a power shower (pumps the flow) are usually the answer.
For the full system-match plus a "do I need a pump?" answer, read our best shower for your water system guide.
Which should you choose?
The honest verdict depends on three things: your water system, what else uses your hot water, and who’s in the household.
For most modern UK homes on a combi boiler or unvented mains system, a thermostatic mixer is the default answer. It gives you the best flow, the safest temperature, and the cleanest look (especially in a concealed install). Add a power shower or a pump only if a basic mixer’s flow is genuinely too weak.
For older homes with gravity-fed systems, you have two equally good answers: fit an electric shower (independent of the boiler, never runs out) or fit a mixer with a shower pump (the upgrade path if you want a stronger, more luxurious feel). The choice usually comes down to whether you want to invest in pumping the gravity system or work around it.
If safety with children, older users or anyone vulnerable matters most, fit thermostatic. The cost difference is small and the temperature control is worth it on its own.
Shower type FAQs
What’s the main difference between electric and mixer showers?
An electric shower heats cold mains water inside the unit; a mixer shower uses hot water that’s already been heated by your boiler or stored in a cylinder. Electric showers work independently of your boiler; mixer showers give a stronger flow if your hot supply is up to it.
Are thermostatic showers worth the extra cost?
For most households, yes. A thermostatic valve holds the temperature steady when your cold or hot supply changes, so the shower doesn’t scald or shock. It’s especially valuable in homes with children or older users, and the price difference over a non-thermostatic mixer is usually small.
Can I use a mixer shower on a combi boiler?
Yes. Combi boilers deliver hot water at mains pressure, which suits a mixer perfectly. Most modern UK homes pair a combi with a thermostatic mixer shower.
Will an electric shower work if my boiler is broken?
Yes. An electric shower only needs a cold-water supply and electricity. That’s why many households fit an electric shower in a second bathroom or en-suite, even when the main bathroom has a mixer.
What is a power shower?
A mixer shower with a built-in pump that boosts the flow rate. Useful in homes with gravity-fed water systems where the pressure isn’t strong enough for a standard mixer. A separate shower pump can do the same job for an existing mixer.
How long does each type of shower last?
A well-fitted thermostatic mixer typically lasts ten to fifteen years before the valve or cartridge needs servicing. Electric showers usually last seven to ten years; the heating element will eventually scale up or burn out, especially in hard-water areas. Brand and water quality both matter more than the type itself.
What type of shower should I fit in an en-suite or second bathroom?
An electric shower is often the smart choice for a second bathroom, because it doesn’t draw on your boiler at all and works independently of the main bathroom. If two people might shower at the same time, that independence is the difference between two warm showers and two cool ones.
When you know which type suits your home, shop electric showers, mixer showers or thermostatic showers, or browse the full showers range.
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