True to a point, but in ancient and medieval times, water in general was seen as unclean, especially for consumption. There was a general preference for fermented beverages such as wine and beer. These beverages weren't nearly as alcoholic as what we consume today (unless you're an upper-class toff), but especially in the case of some forms of wine they were indeed a good source of electrolytes and energy. People just didn't get down with drinking water until there was a reliable way of drinking it without getting some manky disease. People have long learned that water from untrustworthy sources can make you sick, and sought fluid intake elsewhere. It wasn't borne from an understanding of diseases, viruses, bacteria, but from experience. Nowadays, we just take it for granted.
Originally Posted by Larb
The same was true with most bathhouses. People just figured out that oft-changed heated water didn't kill off the clientele as often as unchanged, tepid water, even if they didn't figure it out overnight.
Never minding the fact that nowadays that we tend to disrespect the medical knowledge of yesteryear, with our misunderstanding stemming from those blasted Victorians and other idiot self-promoters from the late-rennaissance, early-modern period. Medical cures didn't begin and end with leaches and blood-letting