Heating water is one of the largest electricity expenses in a typical home, often second only to heating and cooling. Whether you use a tank water heater or an instant electric shower, the principle is the same: turning electricity into heat takes a lot of power, and the longer you run it, the more it adds up.

Rule of thumb: water heating can account for 14–18% of a household's electricity use — and far more in homes with electric showers used by several people.

Why water heating is so power-hungry

An electric shower head commonly draws between 4,500 and 7,500 watts (4.5–7.5 kW) while running. For comparison, a laptop uses around 50 watts and an LED bulb under 10. So a single ten-minute shower at 5.5 kW uses roughly 0.9 kWh — and that repeats for every shower, every person, every day.

A worked example

Take a household of three, each taking one ten-minute shower a day with a 5.5 kW electric shower:

  • Per shower: 5.5 kW × (10 ÷ 60) h ≈ 0.92 kWh
  • Per day: 0.92 × 3 ≈ 2.75 kWh
  • Per month: about 82 kWh
  • At $0.17/kWh that's roughly $14/month from showers alone — and it climbs fast with longer showers or more people.

Numbers vary with your heater's power, your local rate, and how long the water actually runs. Treat this as a model, not a meter reading.

Tank heaters vs. instant electric showers

Storage tank heaters keep a reservoir hot around the clock, so they lose some energy to standby heat but spread usage out. Instant electric showers only draw power while running, but at very high wattage. Neither is automatically cheaper — usage pattern and insulation decide the outcome.

Proven ways to lower the cost

  • Shorten showers. Cutting from 12 to 7 minutes is roughly a 40% reduction on that load.
  • Use a lower power setting (summer/eco mode) when the incoming water isn't very cold.
  • Turn the water off while soaping or shampooing.
  • Insulate a tank heater and lower its thermostat to a safe but lower setpoint.
  • Fix dripping hot taps — a hot-water drip wastes both water and the energy used to heat it.

How to know if it's your main culprit

Watch your bill across a month where you deliberately shorten showers. If the total drops noticeably, water heating was a major share. The X-ray tool on this page estimates that share for you based on your own habits.

Free analysis

Run your free analysis and see possible points of attention at home.

Run my Energy X-Ray

Quick questions

Is an electric shower cheaper than a tank heater?

It depends on use. An instant shower only draws power while running but at very high wattage; a tank loses some standby heat but can be efficient if well insulated. Usage pattern matters more than the type.

Does turning the heater off when away save money?

For a tank heater, lowering the thermostat or using a timer helps. Fully switching off for short trips saves little once you pay to reheat the tank. For long absences, off makes sense.

Why did my bill rise in winter?

Colder incoming water makes the heater work harder to reach the same temperature, so the same shower uses more energy in winter.

Is the estimate on this page exact?

No. It's an educational model based on the figures you enter. Your utility's metered reading is the only official amount.