Laboring at the sink with a sponge must be better than using that energy guzzler under the counter.
A dishwasher is something most folks are not—incredibly efficient. It can save up to 5,000 gallons of water per year compared with scrubbing by hand. That's because it uses roughly five gallons per load, about one-fifth the amount most people use at the sink. And when less water is needed, your home's hot-water heater uses less energy.
Just make sure you don't prerinse, which can squander an extra 20 gallons of water; don't run the machine with only a few dishes inside; and skip settings—like heat-dry or rinse-hold—that are stronger than necessary.
Look for phosphate-free detergent brands. The chemical can spread from wastewater and wreak havoc on lakes and streams, stimulating algae growth that deprives other aquatic plants and animals of oxygen.