This is one of those rare and wonderful cases when what is right lines up with what is easy. Washing your dishes by hand isn't environmentally superior to running them through the dishwater— the latter actually saves water these days.
Experts from Consumer Reports, the Environmental Protection Agency’s Energy Star Program, the Natural Resources Defense Council, and the American Council for an Energy-Efficient Economy all agreed that our modern dishwashers are so energy and water-efficient that you actually end up wasting water if you clean your dishes by hand.
"In order to wash the same amount of dishes that can fit in a single load of a full size dishwasher and use less water, you would need to be able to wash eight full place settings and still limit the total amount of time that the faucet was running to less than two minutes," Jonah Schein, technical coordinator for homes and buildings in the EPA’s WaterSense program, said in a statement.
And don't bother with pre-washing before loading the dishwasher. The modern breed of dishwashers are really good at getting your plates clean—much better, in fact, than plain old elbow grease and a sponge—especially since our hands can't stand the high temperatures used to get your dinnerware squeaky clean.
"Old dishwashers, to generalize, didn’t get dishes very clean unless you pre-washed," says Steven Nadel, executive director of the American Council for an Energy-Efficient Economy. "The new dishwashers, that is not an issue. Almost all of them have what’s called soil sensors. Depending on how dirty the dishes are, they will wash more or less. They will get the dishes clean."
And if you really want to save energy, look for a dishwasher with a "no heat" dry option, which uses a fan to circulate air.
All of this is great news, and just one more reason I wish my apartment had a dishwasher.