This is something that I have heard and read about before, but based on some quick googling, this seems to be a myth. However, could it have been true of a specific time period, location, or social class? For example, is it plausible that the landed gentry of England in the High Middle Ages acfually did consume more beer/wine than water?
I see you've saved me the trouble of sending you to the usual places to disillusion one more person of the Medieval Water Thing, but to provide proof that that myth is indeed a myth, I'll link the relevant section of the VFAQ anyway (Middle Ages, subsection Health and Hygiene, in case your browser doesn't go there immediately), in particular the answers from u/sunagainstgold and u/Qweniden.
In addressing your altered form, we can turn to more u/sunagainstgold.
Of course, this isn't yet complete, and there is room to examine in greater detail the specifics of your question, should anyone be of the inclination.