“Filtering” out fluoride

filter TWBTFLPB1

Systems for removing fluoide from tap water can cost less than $300

Many anti-fluoride campaigners and their sympathisers use “filters” to remove fluoride from their tap water. Despite this, they will often claim the procedure is “too expensive” for the ordinary person – or that it is ineffective.

Fluoride Free Nelson (FFN) combined both reasons in this exchange on their Facebook page.

fluoride size

But she is wrong on both counts. Suitable water filters can be relatively cheap (just do an on-line search  to check this out) and they just do not work by filtering out particles. The argument that fluoride “is so small most filters do not remove it at all” is naive. FFN does not understand how these systems work and her advice is completely unreliable.

Firstly, The word “filter” is commonly used but is technically not correct for “filters” that remove fluoride. Filtration is usually understood to involve removing particulate matter, and not soluble ions. The actual mechanism of fluoride removal is not by filtration of particles.

Yes, some “filters” do not work with fluoride – because they are not intended to. Activated charcoal is great for removing organic matter and tastes – but is not mean to remove anions like fluoride.

Apart from distillation, there are three ways for the ordinary consumer to remove fluoride and similar anions from tap water – anion exchange, surface adsorption and reverse osmosis. Here is a brief description of each method but readers can also refer to a useful local report:

National Fluoride Information Service (2012). Household water treatment systems for fluoride removal.

Anion exchange

This involves attraction of negatively charged anions like fluoride by positively charged surfaces. Water is passed through a bed of anion exchange material which has positive charges on its surface balanced by negatively charged anions like chloride (Cl) or hydroxide (OH).

Anion exchanger

Anion exchange particle. Positive surface charges are balanced by negatively charged ions.

Anions like fluoride in the tap water replace the existing charge-balancing anions on the exchanger. For example:


Fluoride anion in tap water replace chloride anions on the surface of the anion exchanger.

Of course, these anion exchange cartridges eventually become saturated with fluoride or other anions being removed, and their efficiency drops. They are then replaced or recharged by flushing with the proper salt solution.

Surface adsorption

Interaction of fluoride anions and anion exchangers is basically a physical electrostatic one. But some filters rely on a chemical interaction where the fluoride anion reacts with the surface to form a chemical bond. Absorbents like bone char and alumina are common.

Bone char is made from cow bones and is a high surface area, porous calcium phosphate (apatite) providing active calcium for reaction with fluoride. Alumina provides a surface containing active aluminium which reacts with fluoride.

The chemical reactions occurring at the surface of these materials are of the form:

surface reaction


alumina F

Schematic of a water filter using alumina. Source: National Fluoridation Information Service.

The efficiency of both the anion exchange and surface adsorption methods can be improved by the way the filter is set up, the use of pre-filters, etc. And by regular recharging or replacement of cartridges.

Reverse osmosis

This relies on the ability of certain semi-permeable membranes to allow transport of water molecules but not ions like fluoride. So much for the naive concept that fluoride anions are too small to be filtered out of water.

It gets its name from the phenomena of osmosis which is probably familiar to most school children. Remember the experiment where pure water would pass through a membrane into a solution of sugar or salt – but water from the sugar or salt solution could not pass through into the pure water.

reverse osmosis 1

A semi-permeable membrane is a membrane that only allows through molecules of a certain size or smaller. The cell membranes of plants and animals are semi-permeable membranes, they let water molecules pass through while keeping out salts. Image credit: Solar-Powered Desalination Plants.

That creates an osmotic pressure. Reverse osmosis involves applying pressure to the sugar or salt solution (or whatever solution needs purifying). This causes pure water to flow through the membrane and the contaminants to stay behind providing a way of removing ions and molecules from the original water.

This schematic animation shows how reverse osmosis works in practice – although the membranes are rolled into cylinders to provide a greater surface area and increased efficiency.


Image credit: Reverse Osmosis Works

Consumers can use either of these methods to remove fluoride from tap water if they choose. While the equipment varies in price and sophistication, like any household appliance, relatively cheap systems are available.

These do work – just beware of claims made about low efficiency as often measurements are made with inappropriate “filters” like activated charcoal, or on systems that have been used for a time and need recharging.

That “freedom of choice” we keep hearing about is available and it is relatively cheap.

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47 responses to ““Filtering” out fluoride

  1. I think the replacement cartridges for a good filter which does not increase aluminium in the water may cost about 10c or 20c per litre of water.


  2. Brian – supporting data?


  3. Have to put in your email to read the aluminium &c levels after various filters: http://labs.naturalnews.com/Water-Filter-Test-Results.html A good filter seems to be the ZERO. Change every 15 or 30 US gals. Cost in bulk $US10 each. https://www.zerowater.com/filtration-filter-life.aspx
    That is not from Mercola. In his video Mercola talks about a whole house filter which provide very cheap water but does not remove all the fluoride. He is also worried about chlorine coming from toilet bowl flushing water, and also says a 10 min shower gives you as much through your skin as drinking a litre of water.


  4. Brian, you are pathetic. Since when have Adams and Mercola been credible sources of information? Or “Natural news?”

    Adams didn’t even test for fluoride removal – he doesn’t seem capable of utilising a relatively cheap specific ion electrode.

    The Al is a red herring. Your intention is simply scaremongering. The same as Adams and Mercola.

    Perhaps you could tell us if you use any system to remove fluoride and other species you consider unhealthy form you tap water. Or do you use an alternative source.


  5. Ken, at least I gave test results. I don’t think you will get trust that yours are OK by attacking the name of the source of mine, and not giving any.

    I live in Christchurch and don’t use a filter.

    Thanks to Mercola for his advice about letting chlorinated water settle and outgas. I think I shall do that next time I am in a chlorinated city. One place I went had a filter tap but it didn’t taste the best. Maybe aluminium in it; why do you say that is a side issue? If people are against fluoride they are likely to be against aluminium, too, maybe even more so. Are you claiming a logic of being against fluoride but not aluminium?


  6. Ken: “Adams didn’t even test for fluoride removal – he doesn’t seem capable of utilising a relatively cheap specific ion electrode. ”

    My comment that you asked about had been about Aluminium and I gave the data about that. It was a metals test, or “cations” test. Your picture shows “anions” (of which fluoride is one) capture. Anions have a negative charge as does the OH- which the filter substitutes. The ZERO filter has another element to remove cations left in or put in by the anion exchange.
    Christchurch has a moderate level of radon in the water. I wonder about getting a better method of removing that. Normally I boil water but top up the cup with cold out of the tap. I think I might start topping up out of a jug. That will have let some remaining radon out, too.


  7. Brian – you seem incapable of reading. I did not attack “the names” of your sources. I simply pointed out a well-known fact – that they are not credible sources of information.

    But even your citations did not support you attempt at scaremongering.


  8. They did not give the amount of aluminium in before filtering. What are your figures, Ken?


  9. You didn’t read Adam’s properly – he stated how much Al he added.

    Your original comment implied the Al leaked out of the filter – that the filter itself is a source of contamination. That is scaremongering.

    Most councils give chemical analyses for their water and a brief glance shows the concentrations are below the maximum acceptable value.

    I have not seen data for Christi church.

    In Hamilton the Al levels of tap water are lower than the source water – Al is removed during the treatment.


  10. The amount of the test metals they put in varied:

    “To conduct the tests, we created a multi-element “spike” solution containing from 1300 ppb to 2300 ppb concentrations of each of the tested elements.”

    And did you read this, Ken?: “(Minus sign signifies an INCREASE in the element rather than a decrease)”


  11. And how about this scaremongering?: Coliform bacteria can grow in filters.


  12. Yes I did read that – and as there is no information supplied on the filters or methodology there is no way of making any conclusions.

    That is the problem with such sources who refuse to publish their data in a credible and proper manner and place.

    Why do think they got this strange result – experimental error, inappropriate filter, or some other reason?


  13. “Why do think they got this strange result – experimental error, inappropriate filter, or some other reason?”

    I suppose some filter manufacturers are thinking calcium and magnesium to be healthy. Those will be cations so a cation exchange is not included since it would remove them. And aluminium will be present as a cation, too, so remove that and you remove the others cations.

    When alum (the sulphate) is used to coagulate suspended matter in water aluminium level of the water increases. Maybe some filters have alum in them, even if not by intention.


  14. So you can only speculate, Brian.

    Don’t you agree it is unprofessional for a report like this not to include the relevant information. We have no idea what filter cartridges were used and even if they were mean for removal of cations.

    I am picking they weren’t


  15. “if they were mean for removal of cations.

    I am picking they weren’t”

    As I said to leave the calcium in, note your recent article about the need for it.

    But the point is not that the aluminium wasn’t being reduced, it is that it was increasing.

    The article is a start for people to look further.


  16. Maybe alum has been used to activate the alumina:


  17. Brian, you are “picking” these filters were not meant for removing cations!

    Then ask yourself why the hell Adams tested then for that.

    Is he an idiot?

    There is no way to discuss the anomalous Al data for a few filters without knowing what the filters were – or his detailed methodology. I am picking he made calculation errors. It happens.


  18. “Brian, you are “picking” these filters were not meant for removing cations! Then ask yourself why the hell Adams tested then for that. ”

    It’s to make sure they are not contaminating the water, which some of them were!

    And is it your idea that water from filters not intended to remove coliform should not be tested for that? The vid showed no coliform in the tap water before the filters but it did show it after the filters!


  19. No, Brian, he was testing the filters “for removal of Aluminum, Copper, Arsenic, Strontium, Cadmium, Cesium, Mercury, Lead and Uranium.”

    As, I said, I am suspicious of his Al results – and professional person would have made the details available. This is the problem you face when you rely on such bad sources.


  20. Mike seems to have a good mass spectrometer. All the readings appear at once.



  21. What I mean is if the aluminium readings are wrong it is very likely the others would be, too. He has calibrated his machine with a standard solutions. I am thinking that if he got that wrong the readings would all tend to be biased one way. But the aluminium readings go from 100% removal to -52.4% increase.

    Sorry I said before he didn’t give the input figure. He has partially given them “To conduct the tests, we created a multi-element “spike” solution containing from 1300 ppb to 2300 ppb concentrations of each of the tested elements. This spike solution consisted almost entirely of laboratory-grade water (DI water), with a very small fraction (less than 0.1%) of laboratory acids found in element standards for the purpose of matrix stabilization.”
    Need to think how that relates to “usual” water problems.


  22. i have sent this to Mike: “when you were testing effectiveness of water filters you spoke of the nitric acid 0.1%.stabiliser. I did not find it clear what pH that would produce in the filter and whether aluminum could be released because of it.”


  23. i have sent this to Mike:

    You wonder about a lot of things, Brian, that is for sure.

    It’s a pity you don’t wonder why most scientists never reply to your correspondence.


  24. Richard, Ken doesn’t reply when he agrees with me.


  25. Richard or sometimes they me be keeping quiet, like Hilary Clinton who has done no press conferences for over 8 months.

    From one of the Kennedys, challenging the so-called scientific establishment:

    ” Meningitis math

    White Plains: My opposition to new meningitis mandates for every New York State seventh and twelfth grader has nothing to do with autism and everything to do with arithmetic (“Meningitis shot to be rule for schools,” Oct. 28). Meningitis is a rare disease that affects only 390 people nationally last year. FDA and industry testing show the meningitis vaccine to be unusually low efficacy and high risk. The manufacturers’ inserts predict that 1% to 1.3% of inoculated children will suffer “serious adverse effects.” CDC’s Pink Book forecasts that 0.3% of these will die from the vaccine. Of the 400,000 New York school children inoculated annually, some 4,000 will become ill and nine will die in order to prevent around four people from contracting the disease. At between $84 and $117 per shot, and with the requirement for a two-shot series, the law is an $80 million annual windfall for vaccine manufacturers at taxpayer expense. This math makes sense only to the pharmaceutical companies and the Albany politicians who have taken their money. Robert F. Kennedy Jr.”


  26. Richard,

    “It’s a pity you don’t wonder why most scientists never reply to your correspondence”. I don’t think he’s capable of asking himself the question.

    One reason scientists don’t reply to him is that they are used to clarity and precision, both of which are lacking from soundhill.

    A good example is his interchangeable use of “rugby” and “football” in his “idea” about CWF causing harm. He never clearly and precisely names the sport he fantasises is adversely affected by CWF.

    Since he mentions the All Blacks in his fantasies, New Zealanders tend to presume soundhill means rugby, but he’s never clear. The majority of the world’s population have never heard of the All Blacks, never mind such a minority sport as rugby, so outside of NZ all his fantasies are perceived as muddled thinking by a non-scientist.

    New Zealand is one of few countries in the world where “football” could mean the game of “rugby” in colloquial use. But if we ask the NZRU, http://www.nzru.co.nz, we find they don’t use the term “football” at all – they even dropped it from their original name!

    In NZ, football is precisely the sport occasionally known as “soccer”: http://www.nzfootball.co.nz

    Clarity and precision are expected in science, and the lack of both in soundhill’s writing warns scientists away from attempting debate with someone who hasn’t even learned high school science.

    I presume that the lack of clarity and precision that he displays are in order that he can never be proven wrong because he can always say “that’s not what I meant”.


  27. PS, Richard,

    Methinks you are glorifying Mikey well above his status.

    He’s as much a scientist as soundhill😂


  28. There’s “rugby football” or just “rugby” dating from when someone picked up the ball and ran with it. And “association football” or “soccer.”

    So I use “football” to cover both.

    I have in the past included the Manchester/ Birmingham matches which used to be failrly even in wins till about eight years after fluoridation started in Birmingham and it did not win anymore, the best it could do was draws.

    Yes I think Mike Adams needs to look up pH and types of filter. He is trying to just apply the same method as when he checks out foods for lead, &c. I hadn’t realised that when I made my comment about aluminium. Not sure where I might get figures. Presumably the figures for filters should always be exspressed as a table involving the pH of the incoming water.


  29. soundhill,

    You just confirmed my comment.

    You lack clarity and precision when stating your ideas.

    Even now you appear to be conflating (at least) two sports. The NZRU stopped using the term “football” in 2013, so I would advise you to do the same.

    If you are unable to state your ideas with clarity and precision, then how is anybody able to understand the questions you are asking of them?


  30. soundhill,

    “the Manchester/ Birmingham matches which used to be failrly (sic) even in wins till about eight years after fluoridation started in Birmingham and it did not win anymore”

    Clarification needed:
    – rugby or football?
    – professional or amateur?
    – which teams? There are many professional and amateur football teams from both Manchester and Birmingham that would play each other on an annual basis. Of course, there is also a lesser number of rugby teams that do the same.
    Can you understand why clarity and precision is needed in your statements?

    Oh, and I just recalled what you said previously. When we add to today’s statement:
    “I think the effect is in infancy” and “…about eight years after fluoridation started…”
    That suggests you were talking about 8 to 12 year old players! Unless, of course your fantasy, whatever it actually is, is completely wrong.

    Clarity and precision are expected. If you can’t provide them, how can you expect others to answer your questions?


  31. Stuartg I posted this before:
    Last loss of Manchester to Birmingham was in 1978.
    Sorry I was wrong about the start date of fluoridation, 1964. That makes it 14 years, There may be a shorter term in addition to an infancy effect. I need to look into this but silica seems to increase synthesis of pancreatic elastase inhibitor. (somewhere I remember excess potassium may also damage elastase.) So what may it do to vigorous sport performance?


  32. Stuartg: “The NZRU stopped using the term “football” in 2013, so I would advise you to do the same.”

    You and the NZRU in cahoots with the emblem makers.

    Dear Rugby Clubs, Stuartg wants you to change your emblems so that RFC no longer appears on them. And be quick or you won’t be a recognised club.


  33. soundhill,

    I suggest that you read what I actually said and not fantasise about what I think.

    I have no interest in rugby. None. Nil. Nada. Zip. Zero.

    Since it was the decision of the New Zealand Rugby Union to drop the word “football” from their title in 2013, and you are obviously incensed by it, I suggest that you take the matter up with them.

    Clarity and precision are a necessity for intelligent discourse.

    When someone gives an example of how your use of a colloquial name for a sport can result in confusion because of its lack of clarity and precision, you immediately attack the person giving that example.

    You have previously asked for help in clarifying your ideas. Could you explain why, when that assistance is offered, you immediately defend your obfuscation and then subsequently attack the person tendering help?


  34. Thanks Stuartg.

    I do appreciate the opportunity to discuss interaction through written language.

    My camera has a setting for photographing text. I think it may be higher contrast. That can make it clearer to read the the text.

    In that observation I am writing in an analogical manner. Have you been trained to avoid analogies and therefore will say, “Cameras are off topic”? I hope not and that you may rather discuss the point I am making that in order to make things clearer sometimes finer detail is lost.

    Very high contrast makes the image totally black in some places and totally white in all the others. That is OK for text but not for pictures with much of their information being lost.

    I have written often about the two-valued approach. Aristotle advanced logic with the two-valued approach. But “one can’t do justice to Aristotle’s predecessors in Aristotle’s terms.” perhaps “false assimilation of gradable to non-gradable opposites.”


    At some level things are either or. At primary school we use to have skipping games where two people would hold the ends of a long rope and spin it over the heads of a group of kids and then when it got to their feet they would jump. A cleverer pair of spinners could get the rope to go in two halves, one up and one down, so some children would be jumping at a different time to the others. To have the rope in three sections can be imagined. The sound of feet on the ground is quite coordinated. (If the kids try to do individual jumping not in phase with the groups the rope is going to hit their feet.)

    If the school owns a lot of ropes and they are all in use for skipping in that way the sounds of feet will start to make much more of a continuous noise.

    Can you take that sort of analogy into account when thinking of say the “inhibitors” we were discussing acting on gross numbers of molecules?
    For one molecule being inhibited it is two-valued. For many it won’t be.

    So back to the analogy gripe. A search of Google Scholar for “analogy” is interesting. It is used by scientists.

    My little jibe at you about rugby club names (note provincial unions still keep the word “football” in their names) was intended to poke fun at an approach where “you” select or rewrite meanings to suit your argument, maybe for “your” profit if “you” are a drug company.

    There is an example of a common “lower contrast” use of the word, “you,” meaning anyone concerned, and not the audience being addressed, necessarily. From context it is possible to infer the intended meaning of a word. “Aristotle-ising” I find to be an intolerable step backwards.

    “What is context?

    Sometimes context has been conceptualized rather narrowly, as the words surrounding a particular word in question, within a sentence or phrase. In the last three decades, though, it has become increasingly evident that context means many things—even the context relevant to reading just an individual word. Context includes the grammar of sentences and the meanings of words; a paragraph; a whole story or other text. Context is also taken to include the reader’s expectations and purposes for reading; various aspects of the location and situation in which the person is reading; and even the person’s culture and times—in short, the reader’s entire background of knowledge and experience (e.g. Brown, 1997). These various factors operate simultaneously for proficient readers; they usually operate quite unconsciously; and they can affect the identification of single words as well as the reader’s understanding of an entire text. The automatic use of context—of multiple contexts—is a crucial part of the reading process, though most people don’t realize it. ”


    Stuartg I do note you analysed context when you wrote about my comment about, “our energy metabolism.” But I say not widely enough.


  35. soundhill,

    My point was not about whether or not the NZRU uses the term “football”, but your choice to use the colloquial word in a discussion media that requires clarity and precision.

    In a discussion in a pub, your use of the colloquial would be rapidly clarified, but in writing you need to specify which of the codes you actually mean. You cannot use colloquialisms and assume that others thereby understand your precise meaning. Association football, rugby league, rugby union, gridiron, Canadian, Australian rules, Gaelic football – are you specifying one of them, some of them, or all of them? You are the only person to know your meaning if you just use the colloquial “football”.

    You have some vague belief that CWF causes detrimental effects in sport. That we gather. Precisely what effects they are, and in exactly which sport, I am unaware that you have actually made clear. They remain vague, presumably by your choice. That vagueness makes your beliefs almost impossible to discuss, particularly when you say that someone’s interpretation wasn’t what you meant, but never actually clarify what you did mean.

    Take your time to write. Stand back and review before you post. Is what you have written clear and precise? Or can it be misinterpreted? It remains your choice to hit the submit button if your meaning is not clear.

    My advice would be to start by clearly and precisely laying down your beliefs, as would be required for a scientific discourse.

    After all, if you can’t actually say what your beliefs are, how can you expect anyone else to take any notice of them?


  36. soundhill,

    I forgot to add that if you write clearly and precisely there is no need for others to try to interpret, whether using contextual clues or any other method.

    Your words should not require any form of analysis in order to be understood.

    Remember – it’s your choice when to hit the submit button.


  37. Stuartg: “After all, if you can’t actually say what your beliefs are, how can you expect anyone else to take any notice of them?”

    Having a belief seems to imply having come to a conclusion. And note Ken’s motto, “The mind doesn’t work if it’s closed.”


  38. soundhill,

    You are correct. I chose the word “belief” carefully to reflect the impression conveyed by your comments.

    You appear to have come to a conclusion that CWF has some form of adverse effect on “football”.

    As far as I can tell, though, you’ve never precisely stated what your belief is. You haven’t given us any evidence to support the belief. Despite the lack of supporting evidence you have still attempted to defend that belief, mainly by attacking persons who attempt to clarify the sources (if any) of your belief. Your mind does indeed appear to be closed on this subject.

    Someone, I can’t remember who, said that belief is what is left when you lack data.

    Yes, “belief” is exactly the word to use.


  39. soundhill,

    I merely suggest that you reflect carefully on your words before posting.

    Remember, those words are all that others have available to them to convey your personality, intellect, and scientific prowess.

    It’s always your choice what to write and when to post.


  40. This has got to be the first time I read that reaching a conclusion means having a closed mind.


  41. Not a belief that you are making it up to be in your ways that you have.
    I notice something and I point it out. With Rugby and soccer there is quite a pattern.

    I wonder if you have ever said to a patient, “We can’t explain exactly why it works, it is just known that it does.”?

    Should get NZ 4-year-olds’ vision and hearing results soon.

    Keeping mind open for mechanisms.

    Another halide besides fluoride is iodide. If making fermented food products I have seen a recommendation not to use iodised salt since it delays the fermentation process.

    “The human large intestine harbors a complex microbiota containing many hundreds of different bacterial species. Although structure/function relationships between different components of the microbiota are unclear, this complex multicellular entity plays an important role in maintaining homeostasis in the body. Many of the physiologic properties of the microbiota can be attributed to fermentation and the production of short-chain fatty acids (SCFAs), particularly acetate, propionate, and butyrate.”

    I have suggested fluoride might affect the gut process by deactivating some of the enolase of the organisms there. Maybe there are other ways it could work and take the person out of the top bracket of performance.

    It’s not a belief, it is just a notion for exploration, same as I have the notion that fluoride in water could be brought tp 0.5 mg/l the lower end of the WHO suggested range. It’s not a belief.


  42. Much fluoride in ordinary assimilation is absorbed in the stomach as the acid there converts it to HF which easily goes across cell walls. But for sports players drinking a lot it will dilute the stomach acid and won’t wait there but travel on with the fluoride to the large intestine where water is absorbed is my notion. Therefore there will be present a concentration of fluoride which is concert with phosphate could deactivate some enolase.


  43. “During infancy gastric acidity is low,
    especially so in the newborn period (Miller, 1941).”

    Click to access 387.full.pdf

    So newborns drinking fluoridated water or milk formula would be more likely to have the fluoride pass into the lower bowel and possibly affect the infant’s homeostasis via the effect on organisms producing butyrate &c. there is my notion. Especially since infants take in a lot compared to their body weight.


  44. Richard: “This has got to be the first time I read that reaching a conclusion means having a closed mind”

    But you are stuck in two valued thinking, there.

    It doesn’t always mean it, I agree. Please don’t put words in my mouth.


  45. Formula fed infants: “Intestinal lumen is closer to a neutral pH”
    From the uncurated but informative student page:


  46. Brian, if you weren’t so obviously deranged, you would be a comedian.


  47. Richard Christie:
    “Brian, if you weren’t so obviously deranged, you would be a comedian”
    Tut tut Richard, breaking the rules. You must be at a loss.


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