Which is better for the environment: washing dishes by hand or using a dishwasher? So far the conventional wisdom has been it's better to use a dishwasher, but Treehugger investigated and found the answer is a little more complicated. The average dishwasher uses six gallons of water per cycle (Energy Star rated ones use four gallons) and the average faucet flows at two gallons per minute. Using this rough estimate, if your dishwashing load can be done by hand in under two to three minutes, you are better for the environment than your dishwasher. Final conclusion? It's tough to beat your dishwasher.