How Much Does It Cost to Run an Electric Shower?

An electric shower uses its full rating for as long as the water runs. A 9.5 kW shower uses about 0.16 kWh a minute, so an 8-minute shower uses about 1.3 kWh: around £0.33 in the UK and €0.49 in Ireland.

One 8-minute shower a day adds up to about 38 kWh a month: about £10.11 in the UK and €14.87 in Ireland. A household of four, each taking one shower a day, uses about four times that.

Time matters most. Cutting a shower from 8 minutes to 4, as Smart Energy GB suggests, halves its cost. A 10.5 kW shower costs about 10% more per minute than a 9.5 kW one, and a 7.5 kW shower about 20% less.

An electric shower heats cold mains water as it flows through, with no tank. The rating fixes how much heat it can add each second, so the flow depends on how much the water has to be warmed.

A 9.5 kW shower can warm about 4.5 litres a minute by 30°C, for example from 10°C to 40°C. If the mains water is 5°C in winter, it manages about 3.9 litres a minute at the same temperature, which is why electric showers feel weaker in winter.

That flow is low compared with other showers. Smart Energy GB, citing Water UK, says a power shower can use 13 litres a minute. Heating less water takes less energy, which is why electric showers are fairly economical with both water and heat.

At 9.5 kW on a 230 V supply, a shower draws about 41 amps. That's why it needs its own circuit from the consumer unit, with cable and a breaker sized for its rating.

In Brazil, many homes heat shower water with an electric showerhead, the chuveiro elétrico. Models come in 127 V and 220 V versions to match the local supply.

On their hottest position, Fame's KiBanho 4T is rated at 5,400 W at 127 V and 6,800 W at 220 V, and Lorenzetti's Advanced reaches 7,500 W at 220 V.

The lower positions use much less. The 220 V KiBanho draws 4,200 W on its hot (quente) setting and 2,600 W on its warm (morna) setting; the 127 V version draws 3,200 W and 2,200 W.

An 8-minute shower at 5,400 W uses about 0.72 kWh. On a 2,200–2,600 W warm setting, the same shower uses about 0.3–0.35 kWh, less than half as much.

Brazil isn't in our price table yet. Multiply these kWh figures by the price per kWh on your conta de luz, or enter it in the calculator.

An electric shower heats only the water you use, so no heat is lost from a tank between showers. A cylinder heated by an electric immersion heater pays the same price per kWh and also loses some heat while it stands.

In the UK and Ireland, mains gas costs much less per kWh than electricity. A shower heated by a gas combi boiler usually costs less per minute, even with a stronger flow.

On an off-peak tariff such as Economy 7, a cylinder heated overnight can also cost less per shower than an electric shower used at the daytime rate. If you only have an electric shower, shorter showers are the biggest saving.

The rating is printed on the shower's data label, usually inside the cover, and in the manual. Use it with your own shower time in the calculator: 8 minutes is about 0.13 hours.

• Shorten your showers: 4 minutes instead of 8 halves the cost. A simple shower timer helps.
• Use a lower power or eco setting when the mains water is warmer in summer.
• In Brazil, use the warm (morna) position whenever it's warm enough; it costs less than half as much per minute as the hottest one.
• Descale the showerhead regularly in hard-water areas, since scale cuts the flow.
• If you have a hot water cylinder on a cheap off-peak tariff, compare the cost per shower before choosing which to use.

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