Water Heaters

Energy Myth: You need really hot water to sterilize dishes and clothes.

Fact: Even at the hottest setting on your water heater, your dishes and clothes are not sterilized. Also, scalding can occur at high temperatures and can injure you or your child.

Home Series Booklet: Water Heaters (PDF)

Energy Saving Quick Tips:

Water Heater:

  • Lower the water temperature. Most water heaters are set at 140° which can scald and cause injury. For every 10° you lower the water temperature, you can save 6% of your water heating energy. If you have a dishwasher with an internal water heater then a setting of 120° is sufficient. Use a thermometer to check. Electric water heaters often have two thermostats-one for the upper heating element and one for the lower heating element. These should be adjusted to the same temperature. See page 6 of Water Heaters.
  • Take shorter showers. Even a 5-minute shower can use 35 gallons of water.
  • Insulate your water heater tank. Older water heaters had minimum tank insulation. If it feels warm it needs more insulation, especially if it is located in an unconditioned area such as a garage or unheated basement. If possible, wrap an extra "blanket" around the water heater (note: do not cover the thermostat and on gas water heaters, only insulate the sides-not the top and bottom). This will save from 5 to 10% of the water heating costs. Note: Newer water heaters are well insulated and might not need extra insulation. Check the owner's manual for details. See page 5 of Water Heaters and pages 27 and 28 of Home Energy Projects.
  • Drain a quart of water from your hot water tank every 3 months. This will remove sediment that prevents heat transfer and lowers the unit's efficiency. Completely drain your water heater once a year. See page 7 of Water Heaters.
  • Install a heat trap above the water heater. A heat trap is a simple piping arrangement that prevents hot water from rising up in the pipes, thereby minimizing standby losses.
  • For other water heater energy saving tips see pages 16 and 17 of Energy Savers.


  • Wash hands in cool water rather than hot water. See page 3 of Water Heaters.
  • Turn off the tap while brushing your teeth. See page 3 of Water Heaters.
  • When filling the bathtub, don't let the water run down the drain until it gets hot. See page 3 of Water Heaters.
  • Install a water-saving or low-flow showerhead. Energy use can drop as much as 50%. Newer models give good results and are comfortable; they reduce the volume of water without reducing the water pressure. If a half-gallon milk carton fills in less than 10 seconds your shower head is using too much water. A low-flow shower head will pay for itself in about 2 months. See 30 Simple Things and page 2 of Water Heaters.
  • Take showers instead of baths. See page 2 of Water Heaters.
  • Repair leaky faucets because the drips can significantly increase your energy bills over time. See page 3 of Water Heaters.

Washing Machines:

  • Unless you have a low-volume setting, run the washer only if you have a full load. See page 4 of Water Heaters.
  • The warm-wash/cold-rinse setting uses 65% less energy than the hot-wash/warm-rinse setting. See page 4 of Water Heaters.
  • For heavily spoiled clothes, treat the stained areas before loading. See page 4 of Water Heaters.
  • Always use cold water for the rinse cycle. See page 4 of Water Heaters.


  • Run the dishwasher only with full loads. See page 4 of Water Heaters.
  • Turn the dishwasher off at the start of the dry cycle. Open the door and let the dishes air-dry. See page 4 of Water Heaters.
  • Install pipe insulation on your hot water pipes leading from the sink to the dishwasher. See page 6 of Water Heaters.


  • When purchasing appliances that use hot water (dishwashers, washing machines) consider purchasing a high-efficiency Energy Star qualified product.
  • A tankless or on-demand or instantaneous or point-of-use water heater only heats water when it is demanded and does not keep a reservoir of heated water on hand for anticipated use. These systems are most practical for small apartments, single-person households or vacation homes. See pages 11 and 12 of Water Heaters.
  • For electric water heaters, install a timer that can automatically turn the hot water off at night and on in the morning. A simple timer can pay for itself in less than a year.