Whether to Machine or Hand Wash

QUESTION: Which is more energy efficient, washing dishes by hand or using a dishwasher?

ANSWER: It depends on the dishwasher, how you use it and the way you hand-wash the dishes. Keep in mind that the second largest use of energy in home is for hot water. Space heating is first, and refrigerator is the third.

According to a study conducted by Ohio State University, an average dishwasher uses about 10 gallons of water, where it takes about 16 gallons of water for the same amount of dishes washed by hand. But, if the dishes are hand washed using the sink or a dish pan for washing and rinsing, then it requires less water than the dishwasher. Newer, efficient dishwashers use as little as 5 gallons per cycle, which also requires less energy to heat the water.

Water heating accounts for about 80% of the energy used by dishwasher. Since a 140 degree temperature is recommended for better dish-washing performance, most dishwashers now have an internal water heater called a booster heater, which raises the water temperature to 140 degrees F when the dishwasher is in use. This allows you to set the household water heater temperature to 120 degrees to increase the efficiency of the heater.

To save energy and water on dishwashing, here are a few tips:

Dishwasher

--Wash only full loads.

--Avoid pre-rinsing, just scrape, clean and load.

--Load items properly.

--Use the no-heat dry feature, or open the door to air dry the dishes.

--Use the energy-saving cycle whenever possible.

Hand washing

--Use the sink or dish pan for washing and rinsing dishes.

--Install a low-flow kitchen sink aerator on faucets.

Prepared by Loossik Kearsley of the Education and Information Network of the Washington State Energy Office.