Home energy · Heating
Electric versus mixer showers: energy and water costs
An electric shower heats cold water as it flows; a mixer shower uses hot water from your boiler, cylinder or heat pump. Compare them for the same length of shower and the same flow, and count water charges separately.
Updated 2 October 2026 · energy.org.uk editorial team
How they differ
- Electric shower. Its power rating, often around 9 kW, is drawn the whole time it runs. Because the heater's power is fixed, the flow is usually lower: a 9 kW shower can warm only about 4 litres a minute by 30°C.
- Mixer shower. Mixes hot and cold water. The energy cost depends on how the hot water is heated: gas, immersion or heat pump.
- Power shower. A mixer shower with a pump. Higher flow uses more hot water and more water overall.
Check
What to check first
- Your shower's power rating (electric) or flow rate (mixer), in litres a minute.
- How long your showers last. Minutes matter more than shower type.
- How your hot water is heated for a mixer shower.
- Water charges. If you have a water meter, you pay for every litre of water and sewerage as well. These are not included in energy calculators.
Comparing the energy
- Electric shower: kW rating × hours running × your electricity rate. The appliance calculator does this.
- Mixer shower: litres (flow × minutes) heated by about 30°C, priced for your heat source. The hot water calculator has a one-shower option.
Do
Practical next steps
- Time a typical shower, and check the flow or power rating.
- Compare the two in the calculators above.
- A shorter shower saves energy and water whichever type you have.
Take care
Important limitations
- Electric showers are wired to a dedicated circuit; any change needs a qualified electrician.
- Water and sewerage prices vary by water company.