Activated alumina and reverse osmosis are the only two methods for removing fluoride. Some companies claim that carbon filters will remove fluoride, but this is not correct. Also, all our Fluoride Systems use dual stage filters with activated alumina in the first stage and KDF/GAC in the second. We use the KDF/GAC cartridge to remove any activated alumina that may get into your water. Beware of companies selling a single stage filter with just activated alumina. This setup doesn't protect against activated alumina in your water.