How do I remove fluoride from drinking water?

Activated alumina is also widely used to remove fluoride from drinking water, and to a lesser extent, substances such as arsenic. Normal 'safe' levels of fluoride are less than 4 ppm. Above this level, fluoride causes osteoporosis, central nervous system disorders, and perhaps surprisingly, tooth decay. Prior to fluoridation (adding fluoride), water in the U.S.A. usually has less than 2 ppm. However, most metropolitan water supplies are fluoridated to a level of 8 ppm or more as a result of controversial campaigns promoting the dental health benefits of fluoridated water. Activated alumina filters can easily reduce fluoride levels from .5 ppm to less than .1 ppm. The amount of fluoride leached from the water being filtered depends on how long the water is actually touching the alumina filter media. Basically, the more alumina in the filter, the less fluoride will be in the final, filtered water. Lower temperature water, and lower pH water (acidic water) are filtered more effectively too.