Fluoride is an important element that helps prevent tooth decay, but long term ingestion of fluoride has been linked with health problems like arthritis, weakened skeletal health, negative effects on children’s neural development and even cancer. Many people have therefore started using reverse osmosis systems to remove fluoride from water. But, does it actually remove fluoride?
Reverse Osmosis can remove fluoride from household drinking water. A good quality reverse osmosis filter with appropriate membrane pore size (<0.0001 um), filtration speed and configuration, can remove up to 95% of the fluoride in water.
In this post, we explain why fluoride is added to our water supply and why you might want to consider removing it.
Let’s get started.
What is Fluoride?
Before we get into the details of how reverse osmosis removes fluoride, it is important to gain a bit of perspective on what fluoride actually is.
Fluorides are a group of mineral compounds that contain the naturally occurring element fluorine (F). They are readily found in nature and are often released into soil, water and air from mineral-containing rocks.
However, according to the CDC, approximately 75% of the fluoride intake of the people is attributed to fluoridated water itself, or processed beverages (soft drinks and fruit juice) which uses fluoridated water during their manufacturing process.
The fluorides that reach your system this way are often in the form of salts like sodium fluoride or stannous fluoride.
Aside from drinking water and beverages containing these fluoride salts, we are exposed to fluoride through food containing fluoride, or dental products including toothpaste, mouthwash, fluoride supplements, fluoride gel and foam.
How reverse osmosis removes fluoride
Fluoride is filtered and removed by the semipermeable filter membrane in a reverse osmosis system.
‘Reverse osmosis’ is a unique water purification system capable of removing several different types of contaminants from water. All reverse osmosis systems contain one or more of following filters:
- Sediment filter – used to reduce physical particles like dirt, dust and rust.
- Carbon filter – used to remove volatile organic compounds, chlorine and other contaminants responsible for bad smell and taste.
- Semi-permeable membrane – used for removal of dissolved salts (including fluorides)
In order to remove fluoride, the basic idea in any reverse osmosis system is to use high pressure to pass water through a semipermeable membrane (a sheet, hollow tube or fiber), with tiny pores that allows only the molecules of water to pass.
By preventing any large molecule other than water molecules from passing through, reverse osmosis can effectively filter out contaminants and generate pure water. Fluorides are larger than water molecules and therefore will not pass through the pores of the semi-permeable membrane. Instead, along with other contaminants, fluorides are removed with the wastewater through the drain pipe.
This process keeps repeating in the system- producing pure water and collecting (and then disposing of) residual contaminants separately.
Types of reverse osmosis systems
Reverse osmosis systems can be made in various scales. There are factory scale systems for large volume filtration used for community level or commercial filtration of water. There are also portable home scale systems for regular residential use.
For home use, there are primarily two types of reverse osmosis water filter systems – one with a drinking water storage tank and one without the storage tank (also known as ‘tankless’).
The system with a drinking water storage tank has a tight water container that stores pure water after it has gone through filtration processes; whereas, the system without the tank directly dispenses filtered water in real time without storing it anywhere.
Does reverse osmosis remove all fluoride?
While most reverse osmosis systems do not remove all fluoride, home-scale reverse osmosis systems can still remove up to 95% fluoride from water.
The amount or proportion of the fluoride removed by the reverse osmosis system depends mostly on the quality of the semipermeable membrane used. Good quality systems can reduce the fluoride ion concentration to an optimal range, but not to zero levels.
But what makes a reverse osmosis system “good quality”, though?
A good reverse osmosis system consists of a combination of:
- an appropriate pore size in the semipermeable membrane,
- an adequate speed of filtration, and,
- a robust configuration of parts associated with filtration.
With all this in place, 80- 95% fluoride in water can be removed by reverse osmosis filters.
Why is fluoride added to our water supply?
Fluoride is considered to have preventive effects against tooth decay and cavities.
Trace amounts of fluoride are naturally present in drinking water. However, the amount of fluoride naturally present in water may is typically not adequate for the prevention of tooth cavities. Therefore, fluorides can be added to our water supply system in order to effectively prevent tooth cavities and decay.
Water fluoridation is practiced in many parts of the world as a public health activity. In the US, Community water fluoridation has been practiced in many towns and cities since the 1940s and is considered to have reduced the problems of tooth decay.
Widespread use of fluoride-containing dental products has also been able to achieve the same goal of preventing cavities without public drinking water fluoridation in many countries around the world. Therefore, some argue that community/public water fluoridation is unnecessary and may even be harmful if the fluoride level is high.
Water Purification Guide has more information on the effects of fluoride in our water available here.
Why remove fluoride from drinking water?
On the one hand, sufficient evidence suggests that small doses of fluoride help prevent cavities, but, on the other hand, several health conditions are linked to excess fluoride such as:
- dental fluorosis,
- skeletal fluorosis,
- osteosarcoma,
- neurotoxicity and
- effect on reproductive health
With all these concerns about excess fluoride in water, it’s understandable people want to remove fluoride to prevent any toxicity or negative health impact associated with excess fluoridation.
In fact, the USGS mentions that untreated water from some underground sources may have higher concentration of fluoride ions and exceed the maximum contaminant level drinking water standard of 4 mg/L.
If your water comes from untested underground sources, this means you could still be exposed to high levels of fluoride irrespective of whether the drinking water supply in your area is fluoridated or not. Removal of excess fluoride from such water is very important before using it for drinking.
Does fluoride dissipate in water?
Fluoride is present in water in the form of non-volatile ions and does not dissipate in water. It does not evaporate and will become a part of the solid residue left behind if the water evaporated completely.
Water Purification Guide has detailed information on water filter pitchers and shower filters that remove fluoride, and also read this post on brands of bottled water that don’t contain fluoride.
