As many as 63 million people — nearly a fifth of the United States — from rural central California to the boroughs of New York City, were exposed to potentially unsafe water more than once during the past decade, according to a News21 investigation of 680,000 water quality and monitoring violations from the Environmental Protection Agency.
I'd say that "exposed to potentially unsafe water more than once during the past decade" is pretty far from "20% of Americans don't have clean tap water". If anything, I'd rather say it's impressive that 80% of Americans haven't been exposed to potentially unsafe water more than once in a decade!
https://www.usatoday.com/story/news/2017/08/14/63-million-am...