Does Reverse Osmosis Remove Fluoride in Water?

Author: Rory Mullan - Published: 2021/11/18 - Updated: 2023/01/05

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Fluoride, once held as a highly beneficial addition to water, is now under scrutiny because of recent research. It turns out, adding extra fluoride to public drinking water may not be all that great after all. But, there’s still a lot of debate about this.

Now that we have so much advancement in dental care and health, many argue that there’s no need for the fluoridation of water to continue, which has been going on since the 1940s in the US. What for? Municipalities have been adding fluoride to water as it can help delay or prevent tooth decay.

As much as two-thirds of the American population still receives municipal water that is fluoridated. And the US water board isn’t going to do anything about this it seems, regardless of the science supporting not to add fluoride.

Don’t get me wrong. Fluoride in moderate amounts is beneficial as it can indeed make tooth enamel stronger. However, too much of it may do more harm than good, causing teeth and bones to weaken.

Since many of us rely on municipal water, which contains fluoride, the only way to get rid of it is using a water filter – reverse osmosis systems being one of the most popular types available.

This guide answer the question, does reverse osmosis remove fluoride from water?


  • Fluoride from water sources can be removed via reverse osmosis (about 85-95%).
  • In fact, among the most widely used household water filters for removing fluoride are RO systems.

Does Reverse Osmosis Remove Fluoride?

Does Reverse Osmosis Remove Fluoride thumbnail

Yes, reverse osmosis removes fluoride from water, thanks to its very thin semi-permeable membrane that rejects even dissolved minerals.

Does Any Reverse Osmosis System Filter Fluoride?

Yes, a reverse osmosis or RO system of any kind can remove fluoride from water. The performance, however, may vary from one filtration unit to another. Good filtration by an RO system also relies on timely and proper maintenance.

How Much Fluoride Can You Remove Using Reverse Osmosis?

Just because a filter is capable of removing an impurity or contaminant from water doesn’t ensure that it can remove all of it. This also applies to RO systems, as they are not all the same, both in terms of performance and size. That said, most RO systems are capable of removing 85 to 95 percent of fluoride.

It all comes down to the quality of the RO membrane, which is what blocks the very tiny compounds of the dissolved salt.

Some RO filters mention their removal capacity. For example, the AquaTru RO system has a 93.5 percent fluoride removal rate. It’s an NSF-certified water filter.

Generally, too, reverse osmosis systems are designed to remove as much as 99.9 percent of water contaminants. This includes minerals, heavy metals, chemicals, microorganisms and more that may be present in your water, too.

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How Does Reverse Osmosis Water Purification Work?

The highlight of a reverse osmosis system is its semi-permeable membrane. This membrane serves as the main filter element with its millions of tiny pores (around 0.0001 microns in size). Water molecules can pass through these pores, but most other molecules and particles cannot. This also applies to fluoride.

Let’s go into further details to make you understand how exactly an RO system works.

When water enters an RO system it’s under relatively high pressure. This pressurized water is passed through the reverse osmosis membrane. The pressure allows the water to permeate through, but most impurities are left behind.

They remain in the leftover water, which is then drained out. So as you can see, RO systems waste some water in the purification process.

It’s also important to note that RO systems take longer than most other filters to process water. This is why most come with a storage tank, where filtered water is stored ready for consumption.

While the membrane is the highlight of any RO system, they are not the only filter element. There also are pre-filters and post-filters that remove leftover contaminants and those that could damage the delicate RO membrane.

For instance, chlorine is a big menace for said membranes, so it must be removed beforehand during the pre-filtration. Activated carbon filters are used for this.

Other Contaminants Removed by Reverse Osmosis

Reverse osmosis systems can remove a lot more than just fluoride. They mostly use multiple-stage filtration to target different sets of contaminants in water. This is why RO systems are hands down one of the most efficient ways of filtering water.

Here are several contaminants a reverse osmosis system can remove besides fluoride:

  • Chlorine and chloramines
  • Chromium
  • Copper
  • Lead
  • Arsenic
  • Sulfate
  • Radium
  • Nitrates and nitrites
  • Phosphorous
  • Pesticides
  • Pharmaceuticals
  • Volatile organic compounds (VOCs)

Farming tractor spraying a field with pesticides

Keep in mind that these contaminants are removed by all stages of a reverse osmosis system, not just the RO membrane.

What Does Reverse Osmosis Not Remove?

Reverse osmosis water treatment is great, but it has its limitations. An RO membrane alone cannot remove the following:

  • Some pesticides and herbicides
  • Chlorine, chloramine
  • Disinfection byproducts and other chemicals
  • Hydrogen sulfide

Fluoride and its Health Effects

As per the American Dental Association, approximately one part per million (ppm) of fluoride goes into most tap water. This amount is technically safe, but we also have to take into consideration that people get fluoride from many other sources.[1]

There’s fluoride in salt, dairy, medicines, toothpaste and even the cookware we use. So fluoride from all these sources plus fluoride from the water we drink can greatly increase the concentration in our bodies, which is then stored in teeth and bones.

As previously mentioned, fluoride is actually beneficial, but only in moderate amounts. As soon as it exceeds the normal daily requirement, it can cause problems.

Here are some of the issues caused by an overconsumption of fluoride:

Dental and Skeletal Fluorosis

Dental fluorosis results in the discoloration of teeth, mainly the enamel, which is the protective top layer. This happens when a child under eight years has had overexposure to fluoride.

Skeletal fluorosis is a bone condition. It results from too much fluoride stored in the bones. It weakens them. Also, the joints can become stiff which, in turn, causes pain.

In some cases, the very structure of the bone may change as ligaments stiffen. This causes problems with movement, restricting the range of motion for some bones in the body.

Neurological Issues

This is one of the gravest concerns when it comes to the fluoridation of drinking water. Fluoride can collect in tissue present in the part of our brain responsible for learning and storing memories.

This brain areal can get irreversible damaged because of fluoride, which can cause problems like impaired mental wellbeing and even insomnia.

Thyroid Gland

The thyroid plays many important roles in our bodies, producing essential hormones. Too much fluoride can impact this crucial gland.[2]

What happens is that it messes up the concentration of thyroid hormones. The concentration of T3 and T4 decreases while the concentration of TSH rises. In simpler terms, the thyroid becomes underactive (hypothyroidism), which can impact the working of other organs as well.

Acute Fluoride Toxicity

Fluoride intoxication only happens under abnormally high consumption of fluoride, possibly over a long period.

This never happens because of fluoride in public drinking water. However, it can happen if you swallow pesticides with sodium fluoride or dental products containing fluoride.

Pros and Cons of RO Water Filtration

To better understand the worth of an RO system, as well as its challenges, you must look at the advantages and disadvantages associated with it. Here’s what you should know:

Powerful Filtration

Even if your main concern is getting rid of fluoride, it doesn’t hurt that RO systems can remove a slew of impurities from water and make it drinkable. Reverse osmosis water filtration can remove hundreds of contaminants, which makes it good for both municipal and well water.

filling glass from filtered water dispenser

Improved Taste of Water

Some chemicals like chlorine can cause the taste of water to be a little funky. RO systems bring a major taste improvement.

Easy Install and Filter Replacements

Systems have improved a lot over the years. This has resulted in easy installation and maintenance.

The maintenance typically only involves replacing filters. A reverse osmosis membrane can work for years (up to three). The filters need replacement within six to twelve months on average. That’s it; there aren’t any major maintenance duties.

Water Wastage

One of the major drawbacks of RO systems is that they waste water. On average, they send three to four gallons down the drain for every gallon filtered.

Mineral Deficiency

Another problem is mineral deficiency. Reverse osmosis removes everything from water. But some minerals in water are actually healthy. Nutritionists go so far as to call RO water ‘dead’ because it has no minerals left, just water molecules.

So if you’re consuming RO purified water on a regular basis, make sure to remineralize it in order to avoid deficiency.

What to Consider Buying a Reverse Osmosis System

Today, there’s no shortage of reverse osmosis systems in the market. However, that doesn’t guarantee that all are great.

Here are some things to keep in mind when looking for a unit:


Essentially, there are two types of RO systems:

  1. Countertop or under sink RO systems: These are point-of-use filters that go over the counter or under the sink and # supply water for only one faucet.
  2. Whole house RO systems: As the name tells, these are big and made for filtering the entire water supply of a house. As point-of-entry systems, these go where the water enters your home.


Of course, taking into account the price of the RO system and your budget are important. But not just that, also consider the maintenance fees.

How long do replacement filters last? How much do they cost? Also, check if they are easily available online or from a retailer.


One way to distinguish the good from the not-so-good, when it comes to water filters, is to look for NSF/ANSI certifications or testing.

NSF certifications not only ensure that a filter does what the company claims, but they also ensure that it’s made of safe and quality materials.

NSF standard 58 is for reverse osmosis systems, so look for that. It is in correspondence with the elimination of contaminants like chromium 6, lead, fluoride and TDS.

Filter Stages

Remember, an RO membrane alone cannot remove all contaminants, so check out what other filters a system uses.

two water filter cartridges dropped in water

Water Pressure and Wastage

Pressure is critical for effective filtration in an RO system. The water pressure should be at least 40 psi. If the pressure is lower than that, it will require an extra pump.

You already know that RO systems do waste some water down the drain. Ideally, you want a system with a 1:1 ratio or better, i.e., one gallon of wastewater for one gallon of pure water.

Installation and Maintenance

Reverse osmosis systems usually feature DIY installation, especially those that go under the sink or over the countertop. You can always have a plumber do it for you, but that will add up the overall cost of putting this system in your home.

If you want to save that money, consider buying a system that offers minimal installation and tool-free replacement of filters.


Reverse osmosis in general and reverse osmosis systems in particular remove fluoride from water – as much as 95%!

This can be achieved thanks to the semi-permeable RO membrane. It only lets water molecules pass through.

In addition, RO systems remove lots of other water contaminants like chemicals and heavy metals.

In other words, reverse osmosis purification is really powerful.

But, it doesn’t come without drawbacks. The process always wastes some water and the permeate will lack healthy minerals.

When buying a reverse osmosis systems, look out for NSF certifications.

Further Reading


Meet Rory Mullan

Rory Mullan Rory has joined the Water Masterz team as a contributing writer. He has covered all sorts of topics in the last several years.

Outside of his writing work, Rory enjoys photographing the Irish landscape and making music!

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