To answer your Guessing Game:

Welcome to Purity City, for better or worse the nicest place to stay in these parts of the post-nuclear wasteland. Some clever folks got a municipal water processing plant working on the outskirts of a city ruin, giving it the largest supply of clean water in the region. Didn't take long for it to become a major trading hub.

SO, assuming Purity City is on Earth, then I would put it Future. Though it could be Present on a different alternative Earth where a Nuclear Holocaust happened around the 90's turn of the century like in most Hollywood movies from the 70's-80's.