Some people like to think they’re super water-efficient doing the dishes, but they’re not; dishwasher saves water.
About that. I know of one study done in Europe on this, and it was paid for by dishwasher companies, and didn’t exclude outliers like the guy who used about 400L of water doing the dishes by hand.
I once measured water and power usage of me doing the dishes by hand, and it was both below what I found online for dishwashers.
If you do 2-stage cleaning (soapy hot and cold clean water), then dishwashers will be better because they don’t. Amount and source of hot water governs if you are more energy efficient. The advantage of dishwashers is that a badly used dishwasher is far more efficient than badly (= wasteful) handwashing, and even efficient handwashing is not much better than dishwashers (though I wouldn’t know how to calculate production and recycling of the dishwasher itself, not even what order of magnitude that is). Which was, as far as I remember, also in the conclusion of the study, unless there has been another one since then.