I suppose water purity is an ambiguous word. What is water purity? or for that matter, what is love? All I know is my vision of drinking ice cold fresh water from a trickling stream has totally changed in it's meaning.
I envision the band 4 Non Blondes singing, What's Up..."Hey! What's going on?"
What's in your water?(USA)
(International) and (safewater).
All I can say is, "Dirty and nasty, but necessary." Hmmm!