Dishwashers actually save energy and water vs. hand-washing. Maybe you save a little energy if you handwash in cold water, but nobody does that and you would need a lot more soap.
>In the past, dishwashers might have consumed 10 to 15 gallons of water per cycle. Modern dishwashers, on the other hand, are designed with water efficiency in mind. In fact, the Department of Energy mandates that full-sized dishwashers can use a maximum of 5 gallons of water per cycle. Energy Star-rated appliances require even lower water usage, at 3.5 gallons per cycle.
>According to a study conducted by the University of Bonn in Germany, washing a full load of dishes by hand uses an average of more than 26 gallons of water. The study also found that handwashing techniques vary widely, with some people using just 8.7 gallons for the task and others using 116!
In other words, if you wash dishes like an average German, hand-washing half a load of dishes is roughly equal to using an old, inefficient dishwasher. And of course the dishwasher advantage gets larger with a modern system.
I have a dishwasher that I never use. Here's why: it's just me and my girlfriend. I usually use two pans (or one pot and one pan) when I cook dinner. They're stainless steel, and need hand washed. The dishwasher will not get everything off. Plus, I don't have an army of saute pans (and spatula's, etc) to use while I load up the dishwasher until it's full.
So, I wash the pans, along with our plates and forks/knives by hand. We used to load up the dishwasher, but after a while it seemed so pointless to put the plates and utensils in there if I'm already washing pans. Just take another 2 minutes to wash them.
If the dishwasher could clean my pans as well as I could, I'd reconsider. Also, if I had a big family, I'm sure I'd just do both.