More can always be said on the matter, especially since Common Knowledge has such a baleful view of Medieval cleanliness that is rather off the mark. For the meantime, we do have previous posts on the matter:

• u/Noble_Devil_Boruta examines the multitude of ways that waste could be dealt with in the Medieval Period,
• and u/Flubb goes into English laws on filth and hygiene.

With the reference to rivers, are you actually asking about how Medieval people got their water? Because I have a separate set of links for that matter.