Not to mention, it's found from the Chernobyl/other radioactive disaster areas that radioactivity first disappears in the bodies of water, so it doesn't make much sense that there's radioactive water. Though, if they went with realism, a lot of other shit wouldn't be true either, and there's some artistic license that can be made. Having an evil group not want to purify the water though, like in Fallout 3, is fucking stupid. Who would be that against something like that? I'll believe a nuclear powered car sure but not that.
Fallout seems to take on this sort of post-Nukepunk/50spunk world, like where steampunk everything is powered by steam, fallout's pre-apocalypse seems to have everything powered by nuclear energy. It assumes the 1950s naive view of the future and twists the fuck out of it.
I'm not a big fan of other parts of the lore though either, like how every setting is basically desert/wasteland, I hope the Boston setting has more green, it seems dumb to think all agriculture/landscape has turned EXTINCT/ARID WASTELAND.
Things I like about the lore though, the people who invented the Vaults liked to experiment with the people inside them and sort them all by occupation, some specific census set, or with different sets of rules or conditions. It's fun to explore these vaults and find out what was the special condition of this particular vault. For example there's one vault that only had musicians in it, but little known to the people inside the vault they put in white-noise aggression-inducing subliminal message generators inside the vault. Eventually all the musicians got violent and killed each other.
But you know, you don't have to explore it. Some people just go in and grab the loot rather than uncovering the funny story. However you want to play the game.