"Natural" Fluoride

Hello.. I am a nursing mother and I have recently stopped drinking tap water due to what I've been reading about the fluoride and chlorine it contains. I also know there are bottled water products on the market such as "Nursery Water" or "Absopure with Natural Fluoride." Is there any validity whatsoever to the notion that children need fluoride? If so, are the bottled waters with "natural fluoride" a safe alternative to tap water, or is this just a total waste? I just want to make sure my son is getting all necessary nutrients and that he is not getting the toxins.

Thanks..