Maybe I missed a thread? What role does Ultra Violet (UV) play in rainwater collection? Is UV a method to prevent freezing?
Agree with keeping systems simple; less complexity = less points of failure.
Folks should consider researching their region to determine their specific water risks so they can take the precautions they need to achieve peace of mind.
Microdoses of Glyphosate (and other chemicals) are worthy concerns for study; especially for long-term effects on humans, animals, plants, and soil.
However, if city or well water isn’t available and drinking rainwater will prevent dehydration, there are multiple readily-available methods to ensure one can safely drink rainwater.
Dehydration is a bad way to go. Within days, dehydration can cause seizures, low blood volume (hypovolemic) shock, and kidney failure. Even for someone at peak health, severe dehydration can cause coma and death. Deprivation of water will kill most humans in less than 10 days.
Bottom line, better to understand and monitor ACTUAL conditions to inform and prepare effective mitigations.