Dishwashers are, in fact, fabulously efficient. They use far less hot water than warning by hand, and the majority of the energy spent on dishwashing is spent on heating water.
> They use far less hot water than warning by hand
This must be based on a horribly inefficient method of hand washing. Google says that a modern, efficient dishwasher uses about 3 gallons of water per load. I just went and measured the volume of my kitchen sink to roughly where it gets filled to when I'm washing an equivalent of a full dishwasher's load of dishes, and it came out to a bit over 3 gallons.
If it's not summer, I then let my hot sink water sit until it's cooled down to room temperature to avoid wasting heat.
