aquatic turtles will do just fine in chlorinated city water. Turtles are hardier then you give them credit for. I would suggest you don't dechlorinate the water, because it can help keep the water a little cleaner. I have two aquatic turtles, both in untreated city water, they are fine.
1.1 Map Turtles, 1.0 Florida Red Belly Turtle, 0.0.1 Musk Turtle, 1.1 Leopard Geckos, 1.1 Bearded Dragons, 1.0 BCI, 1.0 Airedale Terrier