Conventional wisdom holds that washing dishes by hand uses more water and energy than simply loading up your dishwasher. The federal Energy Star program estimates that an efficient machine uses less than half the amount of energy required to wash dishes by hand — plus, there’s all that time you don’t have to spend standing at the kitchen sink.
However, the efficiency equation also depends on your dishwasher’s size and age. Because water use varies among dishwasher models, it’s tough to give a one-size-fits-all answer. It’s possible, but difficult, to make hand-washing more efficient than a machine.
Here are the things to consider:
Older dishwashers use more water, sometimes 10 gallons more per cycle compared with Energy Star-certified models.
A dishwasher with the federal Energy Star rating uses less than 6 gallons of water per wash cycle. Compare that with a kitchen faucet, which runs an average of 3 gallons of water each minute. Cleaning an entire load of plates, cups, utensils and bowls in that amount of time requires almost superhuman speed.
Your dishwasher’s efficiency also depends on its age. According to government estimates, energy consumed by dishwashers made before 1994 can cost you an extra $40 a year in utility bills.
For the dishwasher:
Use your dishwasher’s rinse feature rather than pre-rinsing dishes by hand. Pre-rinsing dishes can use up to 20 extra gallons of water. Modern dishwashers are designed to tackle your food-crusted plates.
Disable the heated drying function on your dishwasher to cut energy use.
Run dishwasher only when full. Try the “light wash” cycle to see if it’s adequate for your dishes.
Scrape excess food; don’t rinse it.
Be speedy. Keep your drying rack handy and work quickly to avoid running hot water unnecessarily.