My family kinda figured this one out a few years back. We used to live in a city and do the whole city water thing (chlorinated, fluoride, etc...). Then we moved to a more rural area and our water is now drawn from a well on our property. No chlorination (apart from the bi annual well chlorination) and certainly no fluoride. When we moved here the dentist had a little spaz out because of the lack of fluoride in well water and they went so far as to give us a nice huge dose of fluoride pills for the kids to chew daily (for their poor little teefers) because apparently within a few months of drinking well water our kid's teeth were going to crumble into dust and self destruct. A resounding "Oh, fuck that" was uttered and the fluoride tabs were dumped the moment we got the the garbage can. 4 years later the kid's teeth are doing great (amazingly, brushing your teeth actually works just fine!!!).