We are way out on the lunatic fringe of water conservation -- we have 30 gallons of fresh water, which lasts us six days. It is used for showering (every night), cooking, dishwashing, and toilet flushing.
The real limiting factor for us is the gray water -- we only have a 25 gallon gray tank, and it fills up in six days. So we have to dump every week.
We use paper plates to cut down on water usage. And I wipe out the dirty pots and pans with used paper napkins in order to reduce the amount of water needed for washing.
Surprisingly, dishes can be washed in a tiny trickle of water. It takes a little patience, but it works! It's like a Navy shower for the pots and pans: get 'em just barely wet. Turn off the water. Use a little soap on a paper napkin. Rinse in a trickle.
And for soap, we use Dr. Bronner's Castile liquid soap. A little drop of that stuff will do the job, and it rinses clean very quickly.
If we had a bigger set of tanks, we would not have to be so fanatical.