The most effective methods to remove fluoride from drinking water are distillation and reverse osmosis. It may be desirable to follow up with the addition of bioavailable minerals as both of these methods remove all minerals from water.
Activated alumina and bone char are also used for fluoride reduction however these are weaker methods.
Activated alumina (aluminum oxide) requires frequent replacement, significant contact time (very slow moving water) and low pH (optimally pH 5 - 6.5) to be effective at reducing fluoride in water. Activated alumina is also used to reduce arsenic V from drinking water.
Bone char (specialty carbon made from animal bones) is another method used for the removal of fluoride from water. Like activated alumina, it requires low pH (below 6.5), very low flow rates and frequent replacement of cartridges to be effective.
Methods that do not remove fluoride from water
Carbon-based filters for chlorine reduction do not remove fluoride from water.
Boiling does not remove fluoride from water. In fact, boiling will concentrate the fluoride.
Freezing will not remove fluoride from water.
Fluoride uptake while bathing and swimming in fluoridated water
There is no clear evidence that significant amounts of fluoride enter the body through inhalation or transdermal absorption while bathing, showering or swimming in fluoridated water. This is fortunate as whole house fluoride reduction is very expensive and not practical to accomplish.