How to Remove Fluoride in Water
This guide will take you through the basics of fluoride, including where it comes from, its associated health effects, and most importantly – how to remove it from your water.
Why Is Fluoride in Our Water?
There are two ways that fluoride gets in our water supply: it naturally leaches in from the surrounding soil, rocks, etc, or it’s inserted into water through a process called fluoridation.
Fluoridation started in the 1940s after a link was found between fluoride in water and better oral health. After determining that communities with naturally-occurring fluoride in their water had fewer dental issues, 62% of cities and municipalities instated fluoridation between the 1940s and the 1990s.
The result of this fluoridation was a 68% decrease in missing or decaying teeth among 12-year-olds from the 1960s to the 1990s as well as increased oral health for other demographics, and these are the main benefits of having trace amounts of fluoride in your water:
- Prevent the growth of harmful oral bacteria
- Remineralize tooth enamel that has been weakened
- Slow the loss of minerals from enamel
- Reverse the early stages of tooth decay
As of today, 73% of the US has fluoridated water. The EPA established an enforceable standard of 4ppm (parts per million) of fluoride, while their recommended standard is 2ppm.
Where controversy comes in is that the latest USPHS recommendation is that only 0.7ppm is needed for promoting dental health. Considering that fluoride is also found in dental products, this has led many to look for ways to prevent ingesting excess fluoride by removing it from their water supply.
Potential Negative Health Effects
Negative health effects from fluoride occur when too much is ingested over a long period of time. Long-term overdose of fluoride leads to a condition called fluorosis, and it has two main forms: dental fluorosis and skeletal fluorosis.
With mild long-term fluoride overconsumption, fluorosis manifests as white staining on teeth. This is a purely cosmetic effect, but over time it can progress to a severe form which actually causes damage and pitting of the enamel.
Skeletal fluorosis, on the other hand, starts with stiff and painful joints and then progresses to changes in the bone structure and calcification of the ligaments when severe.
Other potential effects of consuming too much fluoride include muscle weakness and stiffness, allergic reactions like rashes, low red blood cell counts with eventual blood vessel calcification, and teratogenic effects on developing fetuses.
How to Remove Fluoride from Water?
There are four main filtration methods that will remove fluoride from water:
Reverse osmosis is a filtration process that involves moving water against its concentration gradient across a membrane. The semi-permeable membrane allows water to pass while blocking contaminants like fluoride, but water naturally wants to travel along the concentration gradient to where there are more dissolved contents – which is called osmosis.
Pressure is applied to the water to force it across the membrane, which makes it travel against the concentration gradient – hence the name reverse osmosis. This filtration method is highly effective for a number of different contaminants as well as fluoride.
Reverse osmosis filters are most commonly found as point-of-use systems, which means they only service one faucet/sink. This is because it’s also a very inefficient filtration method – one gallon of filtered water generates four gallons of wastewater. When you try to scale up a reverse osmosis system to service an entire house, the process wastes even more water.
First, the hydroxyapatite forms a close lattice that can adsorb fluoride and other contaminants and exchange them for calcium ions that are released into the water in their place. Contaminants can also interact with and/or bind to the reactive groups on the surface of the carbon or hydroxyapatite and become trapped.
Lastly, free phosphate in the mixture can bind to fluoride and other contaminants and precipitate them out of the water. Bone char is different from granulated activated carbon or carbon block filtration, so make sure your fluoride filter uses the right one.
Compared to other filtration methods, activated alumina tends to be slightly more finicky. For example, fluoride is best adsorbed at a pH between 5 and 6, while arsenic is adsorbed better at a pH of 7. Treating water with chlorine ahead of time also converts arsenic to a form that is more easily adsorbed.
Distillation is one of the most time-consuming and involved filtration methods, which is why it’s rarely incorporated into home filter systems. Even so, it’s one of the best ways to remove fluoride and the vast majority of other contaminants.
What Doesn’t Remove Fluoride?
Distinguishing between bone char and regular activated carbon is important, because granulated activated carbon, carbon block, and even catalytic carbon are not effective at removing fluoride.
KDF media is great for heavy metals like lead and mercury, but it won’t work on fluoride either.
Air injection oxidization (AIO) is often used for well water systems to remove iron, manganese, and hydrogen sulfide, but it’s all but useless against fluoride.
UV purification, while fantastic for killing microorganisms, doesn’t actually filter out any contaminants – including fluoride.
You can usually double-check the product specifications for contaminants removed for a particular filter to make sure the system actually removes fluoride.
Recommended Filter Type for Fluoride
You can get several different types of water filters that work on fluoride, as long as they employ one of the four methods above. Many filter brands will also use a proprietary media blend that may incorporate more than one fluoride filtration method, or potentially a different method altogether that was developed by the manufacturer.
You can find whole-house filters, under-sink filters, countertop gravity filters, and even water filter pitchers that will remove fluoride. Check out our fluoride filter review here to see some of the top filters we recommend.
Reverse osmosis, bone char, activated alumina, and distillation are the four main filtration methods for removing fluoride, and you can find them in a variety of different systems to fit your home’s filtration needs.