You may have heard about reverse osmosis, but not everyone knows what it does. The simple explanation is that it removes salts and minerals from natural water by forcing water molecules through a membrane under high pressure.
But does reverse osmosis remove fluoride? The short answer is yes, along with almost every other natural element found in water.
The jury, medically speaking, is still out on whether drinking water that has been processed via reverse osmosis is beneficial to the human body in the long term.
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Osmosis vs Reverse Osmosis
Before we discuss reverse osmosis, we should understand what osmosis is. It is defined as the “movement of a solvent (such as water) through a semipermeable membrane (e.g., a living cell) into a solution of higher solute concentration that tends to equalize the concentrations of solute on the two sides of the membrane”.
That explanation may not have answered the question of what osmosis is. Breaking it down into simpler terms will clarify what the process actually entails:
- Movement of a solvent means a liquid such as water in which another material, such as salt, dissolves.
- A semipermeable membrane is a sheet such as a cell wall that only allows molecules of a certain size to pass through. The particles that are able to pass through are limited by the size of the membrane pores.
- A solution is a result of dissolving particles such as salt or sugar into a solvent, such as water.
- A solute concentration is the amount (concentration) of particles dissolved in the solution, e.g., a teaspoon of salt in a cup of water.
- The solute is the matter that is being dissolved.
This means that the molecules of a solvent use gravity to pass through a semipermeable membrane, from the side where they are more abundant to the other side where they are less plentiful until they reach an equal level. Reverse osmosis is exactly that: a process whereby molecules are forced through a semipermeable membrane in the opposite direction. This has to happen under high pressure to oppose the natural force of gravity.
How Does Reverse Osmosis Remove Fluoride?
Reverse osmosis removes fluoride and other salts and minerals by grabbing most of the molecules that are not water and stops them from being transferred to the other side of the semipermeable membrane.
Water (H2O) molecules and some others like calcium and carbon are the only molecules small enough to permeate the membrane pores. These pores measure about 0.0001 microns, i.e., 4×10-5 inches. These filters also contain active carbon, which screen gases found in water, such as ammonia, carbon dioxide, hydrogen sulfide, methane, and nitrogen. Only oxygen and carbon dioxide are soluble in water.
Other minerals contained in water include:
This is important as these minerals are vital to the development and growth of healthy bones and organs. A significant lack of these minerals could result in serious health issues, such as fatigue, weakness, headaches, muscle cramps, and heart disease.
Reverse osmosis treated water is less hydrating than normal water due to the lack of electrolytes. These assist in balancing the amount of water that is in your body. Water is vital to the body as it regulates body temperature, lubricates joints and tissues, and generally maintains the body’s cells.
A test on the efficacy of reverse osmosis membranes was published in the open-access journal MDPI in August 2018. The authors’ aim was to determine whether RO membranes were as effective at filtering out pathogens as manufacturers claimed them to be.
It was found that membranes that were older and damaged did allow the passage of viruses and other contaminants to ‘clean’ water.
Fluoride pros and cons
Fluoride is found in dental products such as toothpaste and mouth rinses to protect teeth from decay. Fluorine is a natural element from which fluoride is produced.
Fluoride has other uses, which are probably not so widely known, including being used in medical Positron emission tomography (PET) scans. It can also be found in cleaning agents, pesticides and used in the manufacture of steel and aluminum products.
It has been suggested that high amounts of fluoride can cause medical problems such as with the thyroid, be a possible neurotoxin causing lower cognitive function in newborns, potentially cause bones and teeth to lose their elasticity resulting in fractures and infections and is possibly linked to cardiovascular and skin problems.
Besides Fluoride, What Does RO Remove?
Reverse osmosis is not all bad. It removes bacteria and viruses as well as salts and minerals that are not good for our health, such as arsenic, aluminum, barium, chlorine, lead, nitrate, and manganese.
An RO filter is also effective at eliminating harmful man-made elements, including:
As bacteria molecules in water are larger than H2O molecules, RO is highly effective at filtering them out. Bacteria found in water can be severely damaging to your health. Infections such as the severely contagious Salmonella (caused by raw or undercooked meat or eggs, unpasteurized dairy products as well as poor hygiene) is generally what you suffer from if you develop “food poisoning”.
Shigella, which symptoms include bloody diarrhea, fever, and stomach cramps, and Vibrio, usually caused by undercooked seafood, are other unpleasant bacterial illnesses.
Water-borne viruses are equally virulent and can include gastroenteritis and Rotavirus, which can be lethal for children, the elderly, and people with weakened immune systems are especially vulnerable. Amoebic dysentery and other diarrheal diseases are to be avoided.
Most e. Coli or Coliform bacteria do not cause disease, but some strains can cause severe infection. The bacteria can be found in soil and water contaminated by human or animal waste.
The presence of e Coli is considered to be the best gauge of fecal matter being present and consequently a source of infection. The Centers for Disease Control and Prevention (CDC) states that reverse osmosis will remove almost 100% of bacteria and viruses.
What Does RO not Remove from Water?
Although reverse osmosis is very good at removing minerals from water, some compounds are not so easily eliminated. Volatile organic chemicals (VOCs), some pesticides and solvents fall into this category, such as:
- Carbon Tetrachloride
Dissolved gases such as
- Carbon Dioxide
- Hydrogen sulfide, which produces a rotten egg odor.
Are also successful at permeating the membrane during the RO process.
The pH of the water determines which acids and bases are trapped during RO and which are permeate. Membranes targeted at each element must be used to stop the permeation of these potentially carcinogenic chemicals successfully.
VOCs are found in solvents, paint thinners, air fresheners and aerosol sprays, wood preservatives, dry-cleaning fluids and many other household goods. They are also found in burning fuel, coal, and natural gas.
Commercial or industrial RO systems are available for these types of processes that cannot be processed by a domestic unit. These units not only use RO, but two additional processes – one that removes sediment and a second that uses a carbon filtration system.
What can alternative methods be used to remove fluoride from water for free?
There are alternate methods you can use other than RO to remove fluoride from water at little or no cost. You can try:
- Distilling, whereby the water is boiled, and the resulting steam is captured into a second container. This steam condenses and reverts to its pure liquid form, without the elements it contained in its previous state.
- Activated Alumina is a desiccant and adsorbent which can be used to extract fluoride from water.
- Bone char carbon can be used, where bones are super-heated and added to water to extract minerals, including fluoride.
It should be noted that the last two processes should only be performed in industrial settings.
We have established that reverse osmosis does remove fluoride from water, but it is the only process that will do so successfully. Boiling water will not remove many elements, harmful or benign, including fluoride.
Reverse osmosis continues to encourage debate amongst in the medical field.
Some experts state that drinking RO water regularly will have adverse effects on the body such as:
- Affecting the Metabolism
- Insufficient intake of Calcium and Magnesium
- Insufficient intake of other Essential Minerals
- Potential increased Absorption of toxic Metals from food
Others in the industry state that RO water is perfectly safe to drink, despite the salts and minerals having been removed, as it is reduced to its purest form.
Whether or not you drink water that has gone through an RO process, do your own research, and decide of the risk of reverse osmosis removing fluoride and other basic minerals is good for your own personal health.