As far as water is concerned, I've seen many manufacturers state that their washers only use around 8 gallons of water per use. It sounds like a lot, but depending on your dishwashing habits, you could easily use that much up filling up the dish water, and then with your rinsing. You also want to maximize your dishwasher by filling it up with dishes each time and not running it half full.
The energy consumption should be minimal if you aren't using the heated dry feature. Just let it finish, then open it up and let it dry out over a few hours time.