Automatic dishwashers claim the most water in the kitchens, about 12 gallons per run. The secret here is to make sure the washer is fully loaded before you turn it on, because it is going to use about 12 gallons whether there’s a dinner worth of dishes or just a couple of things.
Don’t bother rinsing the dishes in the sink before you put them in the dishwasher. Scrape them clean and let the machine do the rest. Inspect all connections on the dishwasher to make sure they’re tight and be sure to repair any leaks.