The city of Flint, Michigan, has entered the chat. But in more seriousness there are plenty of mostly harmless impurities in many municipal water systems such as an excess of minerals i.e. “hard water” and water filters can improve the quality of water that is considered clean enough to drink.
I can’t think of any instances where bethesda messed with the original fallout lore before the show, although I haven’t kept up with 76. Outside of that I would say the video games are all in one timeline and the show is the second timeline so that bethesda won’t have to double down on anything in the show.