Does a Dishwasher Save Water? Yes—Even If It’s Not Quite Full

Growing up, your mom might have insisted that you shouldn’t run the dishwasher unless it’s completely full. So many of us believed it was wasteful to run a less-than-full load when we could simply handwash that stack of dishes in the sink, and save water and energy in the process. However, handwashing can actually be more wasteful than running a small load.

In terms of water and energy usage, dishwashers are much more efficient than washing dishes by hand. According to a recent study by detergent brand Cascade, it takes the average person about 15 seconds to handwash a dish. During that time, the sink uses half a gallon of water (a typical faucet spouts four gallons of water every two minutes). By comparison, an Energy Star-certified dishwasher uses less than four gallons per cycle, which means running a load with as few as eight dishes can actually save water.

Of course, running a full load is the most efficient way to use your dishwasher, notes Rebeccah Buurstra, product brand marketing manager at KitchenAid (formerly at Maytag), as the appliance uses about the same amount of water and energy, regardless of how many dishes you load. But the benefits of running the dishwasher go beyond energy efficiency. Using temperatures up to 140 degrees Fahrenheit, dishwashers can increase sanitization for a better clean than you can achieve in the sink. The appliance also allows you to skip rinsing, scrubbing, and drying your dishes, saving time as well as more than 7,000 gallons of water per year, according to Energy Star.

All that energy saving can have a significant impact on your budget, too. Energy Star says that over the typical dishwasher’s 12-year lifetime, washing your dishes by hand can cost you about $1,300 more than using an Energy Star-certified dishwasher. Combined energy and water costs for the average dishwasher amount to just $463 over the appliance’s lifetime.

It’s important to note, however, that handwashing is the best option for some items. “The dishwasher is the best way to clean your dishes, due to the water and energy used and the temperature at which the dishes can be cleaned, but there are some items, due to material and finish, that you do need to wash by hand,” Buurstra says. She recommends handwashing wooden bowls and cutting boards, cast-iron cookware, and delicate items, such as your grandmother’s fine China.

For everything else, though, load up your dishwasher and press Start (even if it’s not quite full).