I read that most people in the middle ages drank beer as their staple rather than water, since so many places did not have clean drinking water. So...
It's a great question with a pretty simple answer
most people in the middle ages drank beer as their staple rather than water, since so many places did not have clean drinking water.
This isn't true.
The myth of constant beer drinking is also false; water was available to drink in many forms (rivers, rain water, melted snow) and was often used to dilute wine.
I read that most people in the middle ages drank beer as their staple rather than water, since so many places did not have clean drinking water.
This is a myth about the medieval period: there was plenty of clean water. Outside of some sieges, there are no persistent, nor widespread, nor chronic references to shortages of clean water anywhere in medieval European sources that could suggest potable water was an issue.
For discussions of fresh water vs alcohol in the middle ages, see How did people (esp. European townsmen) get their fresh water? and How drunk were the people of medieval Europe? (see further discussion here)
Of course any followup questions are welcome.
Other replies have pointed out that people did not get quite that much alcohol.
I'd also like to point out that the incidence of FAS is not super high. Some sources estimate that it happens 30-33% of the time with a daily consumption of 144g alcohol. This works out to TEN modern-strength drinks a day. Anyone who drinks this much is going to have numerous problems.
There have been other studies that did not detect FAS occurrence when the exposure was two drinks per day. The recommendation to avoid alcohol totally is extrapolation from the heavy drinkers that a small risk remains.
This thread might answer your question in part. I don't think the beer people drank was so refined or alcoholic as it is today. The earliest beers were actually more like a fermented porridge than the lager you might buy today.
Now that the myth has been dispelled, a follow up: when/how did this myth arise?
This thread has been really interesting I've learned a lot about alcohol in the middle ages. One thing I think I've learned is that we really do not know what exactly it was they drank. That's kind of discouraging to me b/c I think it would be cool to try and drink something in modern day that would be as close to what ale a person might have drank in the middle ages.
Does anyone know if there is something out there like this?
First of all, they didn't drink "all day". Secondly, the beer was very dilute and weak.