One of the most frequent questions we get is about whole house fluoride reduction.
This is a complicated issue. There really isn't a good “whole house” filter for fluoride. Activated alumina, the industry's standard removal strategy for drinking water filters, needs lots of “residence time,” thus a very slow flow rate. The recommended rate for a standard 9.75" X 2.5" cartridge, for example, is 0.25 gpm — slow even for a drinking water filter. To get even a 3-gallon-per-minute rate for whole house use, you would need multiple 2.5" X 20" cartridges installed in parallel. Not a practical solution.
Activated carbon has been know to reduce fluoride, but its performance depends on several variables, including pH and the general mineral content of the water, so manufacturers seldom claim fluoride removal for carbon filters. (I suspect that this reluctance to make removal claims for carbon is also influenced by commercial considerations: a large percentage of potential customers don't want fluoride removed, so claiming removal really complicates the issue.) In some countries, a certain grade of carbon made from animal bones, called bone char carbon, is regularly used from fluoride removal, but to my knowledge this product is not available in the US.)
The best remover of fluoride is reverse osmosis. It is a proven and consistent performer. Whole house reverse osmosis, however, is very expensive, consumes lots of water, and the upkeep can be troublesome.
To my knowledge, there isn't a good whole house fluoride reduction strategy, and activated carbon is probably the best you can do. That's what we suggest to our customers, but we sell whole house carbon units with the stipulation that fluoride reduction is not guaranteed.
The most practical solution to the fluoride issue, I think — and this is what I have in my own home — is an undersink reverse osmosis drinking water unit and a high quality whole house carbon filter.
(whole house & well units)