Well, there were a lot of young children in those days too. They drank a lot less (I can't figure out how to say that without sounding sarcastic. They drank, but not much).

I drank kvass as a kid in Russia all the time in the summer.

I don't know which is worse for a kid, on average: a light buzz on most days, or getting sick from drinking tainted water.

Probably the tainted water. With tainted water, you're going to vomit or experience diarrhea which leaves you dehydrated. What do you drink then to rehydrate, more tainted water?

Perhaps night time being a time to sleep instead of work was a good factor considering electricity and all not coming about until later. Look at the amish and when they go to bed and wake up.

Umm, who is drinking 2+ pints for lunch every single day of the year and then some more in the evenings? I'm pretty sure that is a lot to drink.