An aside, but it's interesting how quickly people can adapt to the taste of water in a different city or country. Every time I visit a new area or country, I'm immediately unpleasantly surprised by the taste of the water, but within a few days I forget that there ever was a difference and wouldn't even notice what was different if I tried to be conscious of it. I always see people traveling to another country complain that the "water doesn't taste good" there, implying that it is of lower quality or unsafe, and it usually just makes me chuckle because people traveling in the opposite direction will say the same thing.
Of course, this article is about water that is potentially hazardous which is a real problem.
United Kingdom? As far as I know there's been no problems with our drinking water in terms of contaminations. They add fluoride which I think had a positive impact on the health of the nation (citation needed).
https://wfw.ch/wasserwissen/wasserqualitaet-schweiz#/