[jbotz]

One point for dishwashers I haven't seen mentioned is that they get the dishes a lot cleaner than you ever could by hand, because very hot water. Gets the oils off much better than any amount of soap. For what it's worth.

First time I traveled to the US (I was 13) I thought there was something odd about the dishes... they felt strange. I told my host, I said "there seems to be a film of something that feels strange". He thought about it and said, "what you feel is the absence of something... the thin film of oil that you can't get off when you wash the dishes by hand, but the machine can." He was right.

[kazinator]

Dishwasher detergent is a different animal from the liquid detergent people use for washing dishes.

It's not the only "game in town".

I once washed a load of dishes in a laundry tub filled with a pretty strong concentration of Mr. Clean floor cleaner in hot water.

They came out squeaky, sparkling clean, like out of a dishwasher, without any scrubbing.

(Why I did that is that the dishes fell victim top a drain backup: vertical stack clogged somewhere below my floor, causing other people's black, stinking drain water to start coming up in the kitchen sink, and it soiled a bunch of dishes that were in the sink. I had to resort to something strong and anti-bacterial to feel good about those dishes. I still put them through the dishwasher, too.)

[bjourne]

I don't buy that. The scrubbing you do when hand washing must make up for the hotter water.

[haneefmubarak]

The specific combination of hotter water, rinse aid, and modern detergent mix (lipases, proteases, amylases, and surfactants) is actually able to remove certain chemicals that you couldn't otherwise remove via normal mechanical abrasion (at some point scrubbing harder with a harder abrasive will damage the dishes).

This is because the intermolecular bonds between certain food molecules (esp lipids like fats and oils) and the dish surfaces themselves can be remarkably strong. Additionally, it is quite possible for you to instantaneously remove molecules that are sticking due to intermolecular adhesive forces only for them to stick back on as you move said abrasive out of the way slightly.

The only real way you can actually remove such substances without mechanically damaging the dishes is to break down and/or dissolve them into the water so they don't restick to the surface.