Again, you seemingly have very little knowledge of history at all. Outbreaks of waterborne diseases could happen at any time from a single bad water source. Just look up historical rates of dysentery. Humans in the past fermented and drank far more beer like substances for this reason.

Humans in the past also just fucking died... Anti-biotics and the chlorination of water explains the take-off rate of human population starting around 1900. Before then human populations were self limiting (and this goes for most animal populations too), when you get too many people or animals in one place, they pollute their own water. There was no 're-invention' here. Your entire premise sucks and does not reflect reality.