If all the liquids I drink were beer and cheap wine, my doctor would very reasonably assure me that I would die from liver failure within a year or two. Beyond that, there are all the other symptoms of alcoholism and literally constant inebriation. I just don't see how there could be an adult that manages to fight wars or take care of accounting or lead a sermon if they're drunk literally 24/7.
There's always room for discussion but perhaps the section Water, Wine and Beer from our FAQ will answer your inquiry.
While I'm sure there were plenty of alcoholics in those days, I think most of this is based on common misconceptions regarding Medieval drinking.
As you can find from the links, it wasn't actually hard for most people to get fresh water if the wanted. Furthermore, there's actually nothing inherent in the brewing or fermentation process that makes beer or wine sterile. It's modern refrigeration and pasteurization that do that. Before these advances, beer was quite different, but we can find relics of it in parts of the world today. Basically, if people couldn't find fresh water, they couldn't make beer or wine anyway.
While some beer was quite a bit stronger than the ordinary 4-5% lagers we find in much of the world today, much of the beer drunk was between .5-1% alcohol and called "small beer" or something similar. This would have been quite sweet, lightly carbonated, and quite drinkable. Such a beverage is still drunk in some places, but in quite limited quantities. In the Russosphere many people enjoy Kvass, a rye-based soft drink which is essentially unfermented beer. The same thing is called Kaali in Estonia.