Fluoride is injected into drinking water supplies at various locations around Australia in the form of sodium silicofluoride and sodium hexafluorosilicic. As per drinking water standards this is put into the water at up to 1.5 ppm (parts per million) although the average is 1.0 ppm with possible short (a few minutes or hours) spikes over this due to equipment malfunction or human error. These short term spikes will have little effect on the capacity of fluoride removal filters.
Standard carbon filters of any type are unable to remove fluoride without the addition of special media and even when this media added, they will only remove up to 40%. To remove higher percentages requires reverse osmosis, distillation, resin, alumina or bone char.
Reverse osmosis (ie. Aqua Safe ASRO4) removes approximately 96% and requires resin post cartridges to achieve >99.99% reduction. Distillation removes a higher than 96% but is a batch process and is not considered user friendly and therefore not very popular anymore.
Alumina based systems (ie. Aqua Safe AS280) remove approximately 93% of fluoride but are not suitable for use in bench top systems or incorrectly designed under bench systems as very small trace amounts can under some circumstances leach into the water requiring removal with an additional specialised filter
Bone Char made from animal bones has been used for industrial water treatment for many years although the vast majority is not approved for drinking water treatment. Drinking water certified NSF61 granular bone char is available however, contact time with the media is very important for removal making cartridge design critical for performance. Removal rates tend to vary considerably and multiple (4 cartridges/stages) filters will be required to remove approximately 95%.
Reverse Osmosis is the recommended system for fluoride reduction/removal followed by correctly designed alumina and bone char systems. For reduction levels above 99%, we suggest specialised resin deioniser cartridges installed after a reverse osmosis or alumina system. This type of system may then also include a pH balancing and re-mineraliser cartridge to increase the water pH and add minerals back resulting in a 6 stage water filtration system.