[lmm]

> But we own 25 bowls and 40 spoons. When we run out of bowls (that is, when the "dirty" dishwasher is running with a complement of 25 bowls), the "clean" dishwasher still contains 15 spoons. At the next mealtime, we each get a spoon and a bowl. When we're done eating, we put the dirty dishes in… Well, not either of the "clean" dishwashers!

So you end up washing those 15 spoons again. Big deal. Or you notice that you consistently have leftover spoons in the clean dishwasher and put some into storage, or get rid of them.

On average you use more or less the same dishes each day, so you reach equilibrium pretty quickly. You wash a bit of stuff that was already clean. It's no big.

[TeMPOraL]

So you're running your dishwashers inefficiently. It really does feel like a "big deal". You use more water, more salt/dishwasher cleaning chemicals, and more electricity on empty runs. The clean dishes and utensils getting extra wash degrade faster, the machine itself wears off faster too.

Maybe one day someone makes a dishwasher that can do continuous washing efficiently, dynamically adjusting for the number, type and locations of the dirty kitchenware. Until then, it feels super wasteful.

[lmm]

> It really does feel like a "big deal".

It does, but our feelings are likely miscalibrated here. Dishwashers are insanely efficient.

> You use more water, more salt/dishwasher cleaning chemicals, and more electricity on empty runs.

Unlikely. You're still running the same programme at the same frequency (you were always going to run the dishwasher when you ran out of bowls, the only difference is you have some extra clean spoons in the dishwasher when you do).

> The clean dishes and utensils getting extra wash degrade faster

Technically true, but when was the last time you had to replace a spoon because it had worn out? And how much did it cost when you did?

> the machine itself wears off faster too.

Maybe. Not convinced. You're not putting any extra dirt in it, and the sprayers etc. are likely designed to handle a full load (e.g. the shelves will always be balanced, because you'll always have a full set of dishes when you run the dishwasher).

[Karrot_Kream]

Just to emphasize how efficient a dishwasher is with water, I had a clog in my kitchen pipes (turned out to be much deeper than my drain snake could handle and we had two clogs) and the plumber couldn't come in until a few days unless I was willing to pay for an emergency plumber. I would run the sink for 30 seconds and it would clog. But I could run an entire dish load and it would only fill a bit of the sink and everything would drain okay. Now I have a nice modern dishwasher, but it just goes to show that literally handwashing a handful of dishes is probably as efficient as doing an entire load of dishes in the dishwasher.