How we test electric showers

What makes a good electric shower? Our tests find the models that won't freeze you with sudden dips in temperature or burn you with high energy bills
Hardeep ChannaResearcher & writer
An electric shower in a bathroom

Whether you want to wash under a hot shower in winter, or cool yourself down in the summer, the thing that really matters with electric showers is reliability. 

This is why temperature consistency is so crucial to the way we test and rate showers. No one likes the shock of a sudden change in water temperature when a mains tap is turned on elsewhere in your home.

However, our rigorous testing also takes into account other factors, such as water efficiency, energy use and how easy the shower is to install, use and clean. The video below explains how we test electric showers and highlights why a Best Buy model could make a big difference to your morning shower.


Jump to our electric shower reviews to compare all the models we've tested in detail


Video: how we test electric showers

What are Which? Best Buy, Great Value and Don't Buy electric showers?

Which? Best Buy Great Value and Don't Buy badges

Best Buys

Best Buy electric showers perform the best in our tests. Those that score 75% or more are Best Buy showers and come with a firm overall recommendation. That said, you should still read our reviews to check whether the shower suits your home and whether it has any drawbacks that could affect your decision.

Great Value

How much buyers are willing to spend on an electric shower varies and that’s where our Great Value recommendation comes in. These do pretty well in our tests – scoring 70% or more – while also being at least 20% cheaper than the average-priced models we’ve tested.

Great Value showers are the ones to go for if you’re looking for a bargain - some also score well enough to be Best Buys.

Don't Buys

Electric showers that score 45% or below are added to our Don’t Buy list and are ones to avoid. These disappoint in crucial areas – for instance, they may struggle with strong water flow, aren’t easy to use or clean, or can't hold a stable temperature.

How is the Which? score calculated?

How an electric shower fares in each of these tests contributes to its overall Which? test score. But some tests are more important and so carry more weight than others. The overall score ignores price and is based on:

  • 45% Performance
  • 25% Ease of use
  • 20% Shower efficiency
  • 10% Energy efficiency

To make the grade as a Best Buy, an electric shower must score 75% or more in our tough tests.

How we decide Best Buys

Only showers that excel in all the following six areas make it as a Best Buy.

1. How much hot water will the electric shower deliver?

The more water an electric shower can heat in one go the better, as it will help you wash the shampoo from your hair more quickly. So to find the models that will make your morning shower speedier, we rig each shower up in our test lab, set it to the highest power setting and measure how much hot 40°C water is delivered through the shower head.

Showers range from around 8.5kW to 10.8kW in power and, in general, the higher the wattage the more hot water it can put out. But our tests have found a difference in the amount of hot water models with the same wattage can produce.

2. Does the electric shower’s water temperature rise when someone runs a tap nearby?

Testing showers

Most electric showers regulate the water temperature by balancing the pressure of the heated water in the shower unit with the pressure of the cold water coming in from the mains. So when this incoming cold water flow suddenly decreases (because someone has used mains water elsewhere in your home), there’s a disproportionate amount of hot water in the system, which can cause the shower to get uncomfortably hot.

To see which models keep the temperature steady and which creep up to scalding hot levels, we ran a nearby tap in our test lab for 30 seconds and tracked the temperature of the water from the shower. The best barely changed in temperature, meaning you won’t be in for a nasty shock if someone runs a tap elsewhere in your house while you’re showering.

But it was a different story with some: the temperature of the worst model spiked at 55°C, which we think you’d find painfully hot.

3. Does the electric shower’s temperature drop when the mains water is used while you’re showering?

Mira white shower

All electric showers have a safety feature which cuts power to the heating element if it gets too hot. If this kicks in because the mains water has been used at the same time and the shower temperature has risen, it will stop heating water and the temperature will drop.

During our shower tests, we measured how far the temperature drops before the system recovers and the water starts to get hot again – and the results varied hugely. The temperature of some models barely changed, but the worst plummeted down to an icy 11°C. Wash using one of these dreadful models and you’d find your lovely warm shower becomes a freezing cold deluge – we think you'd have to duck out of the shower while you wait for the water to warm up again.

We only make a model a Best Buy if it protects you from big drops in temperature.

4. How long does it take for the shower temperature to return to normal following a temperature drop?

To help you see which electric showers get back to their original temperature quickly following a temperature drop – as well as the ones that take ages to recover – we time how long it takes for each shower to return its hot water to within 3°C of the 40°C starting point.

Our reviews will help you spot those that won’t mean you'll have to stand out of the shower for long if the temperature changes, as well as the mediocre models that will leave you huddling away from the water spray to avoid an icy downpour.

5. How easy is the electric shower to install, use and clean?

A power shower switched on in a bathroom

Some electric showers are simple to install, while others are tricky, come with inadequate instructions and involve drilling new holes to fix the riser rail in place because the brackets aren’t adjustable. In our lab, we install each shower in our test cubicle and rate how easy it is to fit. Find out more about getting a shower installed.

We also rate how easy each shower is to use, from whether the display symbols are simple enough for any guests to interpret straight away to how easy it is to turn the dials and adjust the height of the shower head. We can also tell you which ones are easier to clean than others, and whether any are likely to set your teeth on edge due to the loudness and pitch of their running noise.  

6. Is the electric shower energy and shower efficient?

The cost to run an electric shower will vary depending on its power. Generally, the greater the power, the more expensive it will be, but costs can be managed with different settings, such as an eco mode.

So when we test, we measure the amount of energy a shower uses in 10 minutes on both the high and lower settings. At the same time, we also record the amount of water produced. From this, we get an understanding of how efficient an electric shower is.

Find out how eco shower heads could save you both water and money.