General comments from professionals - 

Fluoride is undesirable even when found in a natural occurance

Fluoride is natural, but that does not mean it is safe or beneficial. Yes, fluoride occurs in rocks such as fluorspar, where it does no harm as long as it stays tightly bound to the calcium in that compound. Another common fluoride mineral is cryolite, which, in powder form, is widely used as an insecticide on crops. Fluoride does naturally occur in water in varying amounts, but as the concentrations of the fluoride increase, the fluoride accumulated from drinking the water increasingly produces a type of harm to the teeth known as dental fluorosis and, at the same time, damage to the thyroid gland and to bones and connective tissue. At even higher concentrations, this "natural" fluoride in the water will produce crippling skeletal fluorosis, which is marked by locked-up vertebrae, severe arthritic symptoms, skeletal disfigurement, horrific dental problems, muscular problems, and mentally diminished. These disfigurements and disabilities show there is nothing pretty about the cumulative effects of "naturally occurring". fluoride and, the lower our exposure is, the better off we are.

But there is nothing natural about the toxic brew that comes from phosphate fertilizer plants and that is used for 90% of the water fluoridation product in the United States. This toxic brew is the most toxic pollution product coming from these phosphate fertilizer plants and must be handled by workers wearing hazardous material outfits, as a momentary splash of this toxic, corrosive, acidic mixture onto the skin, causes long term disability or may even stop the heart, causing death. This toxic brew contains hydrofluosilicic acid, hydrogen fluoride - highly toxic fluoride compounds that only occur when prepared in a lab or a chemical plant, plus arsenic, lead, other toxic metals, and various radioactive elements. Nowhere in nature is such a toxic brew of poisons found, and the fertilizer plants are not allowed to dump it into the nearly river or bay. They are required to dispose of it in an environmentally responsible manner and would have to do so, except for their scam of getting us to drink it by diluting it into our drinking water, under the fraudulent claim of helping protect children's teeth from tooth decay.

Filtration of fluoride. The most complete removal of fluoride from fluoridated water is accomplished by distillation. A home distillation unit is best and the distilled water is best captured and stored in non-plastic containers. Carbon block filters do not remove fluoride from the water and neither do shower filers, even through such filters can remove the chlorine and toxic metals such as lead. A filter using a chemical, alumina (aluminum oxide) to combine with the fluoride and be used to greatly reduce the fluoride levels. Such an alumina filter may be added as an extra stage to a whole house filtration system. Reverse osmosis filters remove the fluoride ion from water with great efficiency when they are new but, after six months or so, become less efficient at removing the fluoride ion. So, to continue protection from fluoride, the RO filter needs to be changed more often. A final option to mention is just getting good quality spring water, water that is naturally low in fluoride. You would be looking for spring water that has a fluoride concentration below 0.2 ppm. If you are buying the water, make sure that you get spring water, not drinking water. Drinking water is just (probably fluoridated) tap water that has been filtered so as to remove toxins such as lead and chlorine, but the fluoride ion has not been removed from that "drinking water."