For the sake of specificity let us take the 12th to 14th century. British Isles or France.

It is often repeated in pop history that people drank fermented beverages regularly. In fact it's repeated so often that you might think that people didn't drink water at all. However I have the sneaking suspicion that this is pretty inaccurate especially for the lower classes. Do we have any idea how common it was to drink water? Would it be a daily thing? Would fermented beverages be drank every single day? Do we have any idea what percent of income might have been spent on buying non water drinks?

Was it common knowledge that stagnant water was unhealthy? What were considered trusted water sources?