How much does it cost to run an electric shower heater?
An electric shower heater is a point-of-use water heating system that warms cold water on demand as you shower, typically drawing between 7 and 9 kilowatts of power. This extremely high power draw is necessary because the unit must rapidly heat water flowing at several litres per minute, making electric showers among the most power-intensive appliances in any home despite their relatively short daily runtime.
Electric Shower Heater running cost calculator
- Per day
- $0.34
- Per month
- $10.34
- Per year
- $124.10
- CO₂ / year
- 292 kg
Based on 730 kWh per year. Adjust the price per kWh to match your latest electricity bill for an exact figure.
At 8000 watts used 0.25 hours a day, an electric shower heater costs about $0.34 per day, $10.34 per month and $124.10 per year on an average rate of 17¢ per kWh — roughly 730 kWh and 292 kg of CO₂ over a year. Enter your own electricity rate and usage in the calculator above for a figure matched to your bill.
The reason electric shower heaters consume so much power comes down to physics and the demands of comfort. When you turn on the shower, cold mains water flows through a heating element—usually a metal coil or resistance wire—that must warm it to a pleasant temperature in just a few seconds. This isn't like a slow water heater that gradually warms a tank; the heating happens instantaneously at the point of use. To raise the temperature of several litres of water per minute from, say, 10°C to 40°C requires enormous amounts of energy delivered in real time, which is why even modest shower heaters rarely draw less than 7 kW.
Your actual energy cost depends heavily on flow rate and temperature setting, two factors you directly control. A high-flow shower head combined with a lower temperature setting will use less energy per minute than a restricted flow at maximum temperature, even though the comfort level might be similar. Many homes with electric showers report surprisingly high usage because people unconsciously run them hotter or longer than alternatives like mixer taps fed by a central tank. If you have a choice between an electric shower and a conventional boiler, running the boiler at night on cheaper off-peak rates—if available—will almost always be more economical over time.
When shopping for an electric shower, look for models with adjustable power settings rather than fixed 9 kW units. Some premium electric showers offer dual-stage elements that let you switch between high and low power, or thermostatic valves that automatically regulate temperature and prevent scalding. These features don't reduce peak power draw, but they do give you finer control over flow and temperature, which translates to less accidental energy waste. Older electric showers often lack any temperature regulation, forcing you to manually balance hot and cold—a frustrating experience that usually results in people leaving the water running longer than necessary.
One common mistake is assuming that newer electric showers are automatically more efficient. In reality, efficiency improvements in electric heating are marginal because resistance heating is already nearly 100 percent efficient at converting electrical energy to heat. What matters instead is how you use the shower: shorter showers, cooler temperatures, and lower flow rates all reduce energy consumption, but these are behavioural choices, not product features. If you're motivated to lower your running costs, focus on how you shower rather than which shower you buy. Installed properly with good insulation on the pipes and a thermostatic mixing valve to prevent scalding, an electric shower can be a perfectly adequate choice for low-income households or properties without mains gas, but it will never be the cheapest option if alternatives are available.
Frequently asked questions
- Why does an electric shower use so much more power than other appliances?
- An electric shower must heat water to a comfortable temperature in seconds rather than hours. It's essentially doing the job of a large boiler instantly and continuously, requiring 7-9 kW of power. Compare this to a kettle (3 kW) heating water that's already sitting still—the shower has to work against flowing water and time constraint, so it needs much higher power to achieve the temperature rise quickly enough.
- Can I reduce the cost by lowering the temperature setting?
- Yes, but only slightly. Lowering the temperature setting reduces how much cold water needs to be heated, so the heating element runs for less time per shower. However, you're still running the full 7-9 kW when the element is active. The bigger savings come from reducing shower duration and flow rate—both of which you control independently of the temperature setting.
- What's the difference between a thermostatic and a manual electric shower?
- A thermostatic electric shower has a built-in valve that automatically mixes hot and cold water to maintain a constant outlet temperature, protecting against scalding and reducing the need to adjust controls mid-shower. A manual shower requires you to balance the hot outlet yourself by adding cold water. Thermostatic models are more convenient and slightly more economical because they're less likely to run unnecessarily, but both types use the same peak power.
- Is it worth upgrading to a dual-rate or low-power electric shower?
- Dual-power models that let you switch between 9 kW and 6 kW can be useful if you're willing to accept a slower warm-up for lighter use days, but the difference in energy consumption is modest. The real value is in the choice itself—you might use low power for summer showers and high power in winter. True efficiency gains still come from shorter showers, not from the shower unit itself.
- Do electric showers work well in hard water areas?
- Electric showers can accumulate limescale in hard water regions, but this is a maintenance issue rather than an efficiency problem. Descaling products designed for shower heads work well, and some electric showers are easier to descale than others due to accessible heating element design. The hard water doesn't make the unit use more energy, but it may reduce flow rate over time if mineral buildup isn't addressed.
- Should I run my electric shower on Economy 7 or night-rate electricity?
- Electric showers typically run during the day when you bathe or shower, so they can't benefit from Economy 7 off-peak rates. If you have a choice between an electric shower and a conventional hot water tank fed by a boiler, the tank can be heated on cheaper night rates, making the boiler option cheaper overall. Electric showers are most sensible in properties without central heating where alternatives aren't feasible.