Plug Count

How many watts does an electric water heater use?

A standard 240-volt electric tank water heater draws about 4,500 watts while heating, roughly 3,500-5,500 W depending on its elements. Heat pump water heaters draw only a few hundred watts in heat pump mode.

Running watts
4,500 WTypical; 3,500–5,500 W across models
Starting watts
NoneNo motor surge
Per day
13.5 kWh24 h of use, cycling
Current
18.8 AAt 240 V while running

Figures checked against DOE, ENERGY STAR and manufacturer data on . Your model's label is the final word.

Watts by model and setting

Most electric water heater models draw between 3,500 and 5,500 W while running; a typical one draws about 4,500 W. Assumes a 4,500 W element heating about 3 hours a day for a family of four. ENERGY STAR estimates a heat pump model saves about 3,760 kWh a year for such a household.

  • Element wattage: most 40-50 gallon residential tanks use 4,500 W elements; some use 3,500, 5,500 or 6,000 W
  • Most tanks have two elements wired non-simultaneous, so only one heats at a time
  • Hot water use, incoming water temperature and the thermostat setting drive how many hours it heats
  • Heat pump (hybrid) water heaters move heat instead of making it and can be two to three times more efficient, falling back to elements in high-demand or cold conditions

Running an electric water heater on backup power

This is a 240 V appliance. It needs a generator with a 240 V outlet or a transfer switch or interlock installed by a licensed electrician; most portable power stations only supply 120 V.

  • A 4,500 W, 240 V element is too much for small generators and most portable power stations; usually leave it off during outages
  • If you do power it, it needs a 240 V generator through a transfer switch or interlock; never backfeed
  • A full tank stays hot for many hours, so short generator runs can reheat it before showers
  • Heat pump water heaters set to heat-pump-only mode draw far less and are much easier to back up

Add it to the generator calculator

Questions people ask

Can a portable generator run an electric water heater?

Only a 240 V generator of roughly 7,000 W or more, connected through a transfer switch, can run a 4,500 W element alongside a few other loads. Most people skip it during outages.

Do both elements in a water heater run at once?

In most residential tanks, no. The elements are wired non-simultaneous, so maximum draw is one element, typically 4,500 W.

How much less do heat pump water heaters use?

ENERGY STAR says they use less than half the energy of a standard electric tank, saving a family of four about 3,760 kWh a year.

Sources