Even before that, clean water was hard to find, so most people drank slightly alcoholic beverages all day long.

This is a common myth; I don't know where it came from but it's a flat out myth. Still water from well reservoirs was not clean; running water was just as clean as it is today. You can walk up to just about any stream in the world (that doesn't have an industrial plant dumping into it) and drink out of it and be completely okay as long as you are acclimated to that regions diseases (which if you are from there...you are).

Here is a great post on the matter.

Medieval towns and villages had various ways of dealing with cast off and effluent which did not merge with the drinking water. For small villages and rural homes the toilet was a few steps away into the forest. In the larger towns you can still find homes that have medieval toilets (for example, the castle I am staying at is built up against a wall and on the other side of that wall is a run off trench; in the cellar is a stone toilet from 13th century with a wall outlet/runoff into the trench; it is now where the electrical comes in!)

Some had 'gutters' which pushed off effluent into the surrounding landscape. Where there was faster running river the town could dump straight into the waterways and it would not affect health, even slow moving waters would do, as it was rare to pull drinking water from the river - there aren't many medieval sources that talk about rivers for drinking, it was for washing and leisure.

. . .

The sources of potable water were generally wells, sometimes artesian, sometimes spring fed, and often in the center of the village as a common resource. These wells were more likely to run dry than to be infected with human feces. Large villages, cities and some castles would have cisterns to collect water, either through surviving aquaducts, from springs, or from rainwater. Again, the castle I am at has an underground medieval cistern, about 5 cubic meters large.

By the way, artesian wells were invented well before the modern era and they kept water flowing in the wells which helped reduce contamination. I know it may shock some of our readers here but people in the past weren't stupid.