Water Heater Temperature

Most of us operate day in and day out blithely unaware of our water heaters
– that is as long as we have an ample supply of the warm liquid to comfort
our aching muscles in the evening and shock us into awareness during the wee
morning hours. But an appliance that provides so much comfort shouldn’t
just be taken for granted. By showing your water heater a little understanding
and TLC, it will perform better and require less maintenance over the long haul.

What temperature is too high?

Water heaters often come set at 140°F – some as high as 160°F.

These temperatures are excessive and increase the risk of scalding.

As a rule of thumb, for every 10°F that you lower the tank temperature,
you’ll realize a 13 percent savings on your water heating bill.

Water temperatures above 140°F cause sediment to develop more quickly.

What temperature is too low?

Harmful bacteria (Legionnaires’ disease) can form in the tank and pipes
if temperatures are below 120°F for extended periods.

What temperature is just right?

ENERGY STAR recommends that settings be adjusted to 120°F.

Typically between the medium and low setting on the dial.

Idaho Power recommends settings between 120°F and 130°F – depending
on how far the faucets are from the tank.

Make certain the water flowing from the faucet furthest from the tank is 120°F.

Test by holding a standard thermometer under the faucet

If I lower my water temperature, will my dishes still be clean?

The short answer is YES.

Occasionally you hear that some dishwashers require higher temperatures

Since 1994, all standard-sized dishwashers have been manufactured with booster
water heaters. Since dishwashers have an average life of about 11 years, there
probably aren’t a lot of units out there where this is a concern.

If your domestic hot water is supplied by gas and you want to minimize the use
of the electric booster heater, you can run the tap until the water is hot before
turning on the dishwasher.

Dishwashers are complex these days and have sensors that determine ideal temperatures
for the selected wash cycle and soil level of the load. High pressure jets frequently
eliminate the need to pre-rinse dishes and more efficient controls and settings
are standard on ENERGY STAR models.

Some water-volume controls require dishwashers be installed on level.