Alcohol concentrations below 50% have sharply diminished disinfecting utility, and wine and beer have alcohol concentrations in the neighborhood of 5%. However, the water in wine comes from grapes, while the water in beer may have been boiled prior to brewing. If the beer or wine was a commercial product, the brewer might have taken extra care in sourcing ingredients in order to protect their reputation. Beer and fungal contamination is a problem for the beer industry. Many fungi are adapted to the presence of small amounts of alcohol (indeed, that's why fermentation works at all), and these beverages are full of sugars that bacteria and fungi can metabolize for their growth. People might have noticed that certain water sources could make you sick, but if so, they could also have noticed which sources were safe to drink. On the other hand, consider also that people continued to use and get cholera from the Broad Street Pump. If John Snow's efforts were what was required to identify such a contaminated water source with the benefit of germ theory, then it would be surprising if people would have been very successful in identifying delayed sickness from a contaminated water source unless the water source was obviously polluted. An appeal to metis only seems to support the idea that people avoided drinking water to avoid getting sick if we also assume there were no safe water sources around, if this persisted long enough and obviously enough for people to catch on, and people saw no alternative but to give up on drinking water. I also think it's interesting that several religions have banned or discouraged alcohol consumption, and have also required or prohibited certain behaviors for reasons of hygiene, and yet, AFAIK, no religion has ever mandated that its followers drink alcohol and refuse water. Instead, we have numerous examples of religions promoting the consumption of water as more spiritual or healthful.