I have to respond here with "WTF are you talking about". You are engaging in the https://en.wikipedia.org/wiki/Naturalistic_fallacy without use of your critical thinking facilities. Any water source that has rotting plant material, or is exposed to the feces of animals puts you at high risk of serious illness. Some water sources will have natural bacterial contamination and/or mineral contamination (think arsenic).
Absolutely huge portions of the human population died to water quality issues before the 20th century.
Absolutely huge portions of the human population died to water quality issues before the 20th century.