it SHOULD be up to the individual whether they want fluoride in the water they're drinking. this is not like vaccines, where unvaccinated people are a risk to everyone around them.

edit: adding this https://www.hsph.harvard.edu/magazine/magazine_article/fluoridated-drinking-water/

and key takeaway: The Cochrane report also concluded that early scientific investigations on water fluoridation (most were conducted before 1975) were deeply flawed. “We had concerns about the methods used, or the reporting of the results, in … 97 percent of the studies,” the authors noted. One problem: The early studies didn’t take into account the subsequent widespread use of fluoride-containing toothpastes and other dental fluoride supplements, which also prevent cavities. This may explain why countries that do not fluoridate their water have also seen big drops in cavity rates (see chart).