Fluoride is a small charged ion, which puts it outside what most household filtration does. Carbon adsorbs organic molecules and passes it. Sediment cartridges strain particles and it is not one. Softeners exchange hardness minerals and leave it alone. Three technologies do reduce it, and before buying any of them there is a free check worth making.
Check whether it is there at all
Many supplies are fluoridated, many are not, and some groundwater carries fluoride naturally. The EPA notes that every community water system publishes an annual Consumer Confidence Report and maintains a finder for them, and that report states whether fluoride is added and what was measured. On a private well only a laboratory test answers it, since natural fluoride varies by aquifer and has no taste or appearance. Establishing this costs nothing on a municipal supply and prevents buying equipment for a problem you may not have.
Reverse osmosis, the usual household route
An under sink reverse osmosis system rejects fluoride along with most other dissolved material, and it is the practical answer for most households: one installation, a wide range of contaminants addressed, and treatment where it matters, at the drinking water tap. The trade offs are the usual ones, cabinet space for a stack and a tank, a drain connection, a reject stream and annual prefilters. A remineralization stage afterwards restores the taste that the membrane takes out.
Activated alumina and bone char
Activated alumina is the medium used specifically for fluoride, including at municipal scale, adsorbing it onto its surface. Performance depends on contact time and on pH, and capacity is exhausted silently, so it runs on a measured schedule rather than on appearance. Bone char works similarly and is chosen by some households on preference. Both are specialist media rather than general purpose filters, and both need the flow kept slow enough for the contact they require, which a small inline cartridge at full tap flow will not provide.
What does not work
Boiling concentrates fluoride, since water leaves as steam and the fluoride stays. Standing, freezing and carbon filters do nothing useful. Water softeners do not target it. Distillation does work, at the cost of speed and energy, and is worth mentioning for completeness. Because ingestion is the exposure route, point of use treatment at the kitchen tap is sufficient and far cheaper than treating every gallon entering the house. Our at home filtration guide covers matching a system to what a test actually found.
Questions people ask about how to remove fluoride from water at home
Does a carbon filter remove fluoride?
No. Fluoride is a small charged ion and carbon adsorbs organic molecules, so it passes through essentially untouched.
Does boiling help?
No, it concentrates fluoride, because the water evaporates and the fluoride remains behind.
How do I know if my water is fluoridated?
Your utility's annual Consumer Confidence Report states it, and the EPA maintains a finder. On a private well, a laboratory test is needed.
Do I need to treat the whole house?
No. Ingestion is the relevant exposure route, so treating drinking and cooking water at the kitchen tap achieves the same result far more cheaply.