Make your own fluoride filter, from ‘charred’ bones – BIOCHAR aka BONE CHAR!

Bones are amazing – and can be used in many different ways.  Bones regenerate many times inside of our bodies and the bodies of animals, millimeter by millimeter.  Bones store minerals, and have a interesting structure.  Some tribes native to the California area hunted rodents, and crushed/ate the entire animal, including the bones to benefit from the minerals, etc.  Today, we often make mineral-rich bone broths to nourish ourselves.  Sepp Holzer in Austria uses bones to make a ‘bone sauce’, which he applies to saplings to deter deer and other creatures from eating and damaging them.  I was only a little surprised, and thoroughly delighted to learn that bones provide yet another service: water filtration.
 To use bones for water filtration, the bones must be burned at high temperatures in a low oxygen environment.  This process results in biochar.   Typically ‘biochar’ is the term used to describe this process when done at home, on the farm, or in smaller amounts.  ‘Activated carbon’ is the term used when this process is done using specific commercial industrial processes. 
Biochar can be made from various biomass, such as wood, or coconut shells (often used for commerical activated carbon), or bones!  The resulting biochar from each material will have different properties.  To learn more about biochar, read the post called: “Use burned biomass to clean/filter/purify water – BIOCHAR!
When the biochar is made from animal bones, it is sometimes called ‘bone char’, and unlike the other materials I mentioned, biochar made from bones has the unique ability to remove fluoride.  Thus, for those living in areas where the municipality is still attempting to ‘medicate’ the public by adding the neurotoxic, IQ-lowering, industrial aluminum processing by-product known as fluoride, then biochar made from bones could be very useful in your water treatment system.
If biochar is made sub-optimally at temperatures lower than 800 – 900 degrees C, the biochar will be less effective in water filtration.  This is the case as far as I know, regardless of what material is used to make the biochar, whether it be wood, coconut shells, bones, or other types of biomass.

 In the graph directly below, Josh shows that biochar, when made correctly at high temperatures (900 degrees C), performs better than biochar created at low temperatures (350 degrees C), or intermediate temperatures (625 degrees C).

different types of char and their filtration performance


Josh and his lab team measured performance of high temperature biochar to be on par with or better than commercially made activated carbon used in carbon filters, such as the ones Berkey sells.  This is one of the most amazing things I have ever learned or found on the internet. 

Some people in the DIY community have taken matters into their own hands, and have begun testing their success with fluoride meters.  They found water filtering products, such as the ‘Waterite’ reverse osmosis (RO) filter, to be effective in filtering out fluoride the first year, and a bit less effective the second year, with .05 PPM of fluoride found in the filtered water.  The best performance was found when the RO membrane was replaced at least every three years.  One should remember that RO membranes will become damaged and not work properly if the RO membrane is exposed to chlorine in the source (tap) water, which is why the pre-filtration cartridges must be used and replaced regularly.  I’m not sure how one would test in order to know how often they need to be replaced.  Waterite RO products might be found from distributors for around $250 or less.


I was surprised to learn that fluoride meters, such as the Low Range Fluoride Colorimeter from Hanna(accurate (+-0.1 PPM)), requires the use of reagants that contain mercury.  As with most common water tests, to determine the amount of a substance in a water sample, a chemical (in this case, mercury) is added to the water, and the resulting color or chemical change communicates how much, if any, of the substance in question is in the water sample.
Mercury reagents available to react with and detect fluoride in water.
“These reagents follow the SPADNS Method in which the reaction between fluoride and the reagent causes a colorless complex in the sample. By simply adding 2 mL of SPADNS reagent to two cuvettes, and subsequently 8 mL of deionized water to one and 8 mL of sample in the other, the reaction will take place and the HI729 will determine the concentration from the color that is produced. The results will be displayed in ppm of fluoride. These reagents are designed to be used with samples that have an expected range of 0.00 to 2.00 ppm (mg/L) fluoride.”
I was very surprised to learn that mercury is required to react with and detect fluoride!!!    Fluoride is a neurotoxic substance and should never be added to water.  No ‘medication’ should be added to the water supply.  I don’t believe fluoride is a medicinal substance, but there are still many people who believe it is medicinal, or necessary in order to maintain healthy teeth.  The Fluoride Action Network’s website has incredible information regarding this topic.  To read more, please visit the post about fluoride here.
 To find more information about Reverse Osmosis and other water filtration methods, read the post: Drinking Water: Solutions & Filters.
The DIYers I have mentioned recommend biochar, made from bones, as an alternative to reverse osmosis (RO) or other filtration methods.  They suggest using bone char in combination with a post filter of coconut shell activated carbon, in order to remove the taste and odor of the bone char which may remain (meaning, the water would first go through a bone char filter or tank filled with bone char to remove the fluoride (which coconut shell biochar does not do), and then go through a filter or tank filled with biochar made from coconut shell to remove the odor and taste of the bone. 


As is the case with most filtering media, water must be in contact with the bone char for a minimum required time in order to effectively remove fluoride (or other contaminants, for that matter).   The smaller the size of the filtering system/container, the less contact time will result, and therefore, the less potential fluoride removal.  Therefore, sizing the system/container can be an important factor.  “Empty Bed Contact Time” (EBCT) is the industry term typically used for measuring the  time the water comes into contact with the filtering media, which is the volume of media used in the filter, divided by maximum flow rate. 
Here are some approximate EBCT (with bone char) guidelines to keep in mind based on home experiments kindly shared by DIYers: 
    • < 10 seconds EBCT = poor results 
    • 15 seconds EBCT = acceptable results.  
    • 30 seconds EBCT = really good results (ideal EBCT target)

Again, the most critical factor in Bone char filters and the reason most commercially available filters are not effective in removing Fluoride is the lack of contact time.  The filter container must be large enough to facilitate enough contact time with the bone char.  If there is not insufficient contact time, fluoride will not be effectively removed or reduced.  
Bone char filters that are manufactured as ‘ready to install’ are available for purchase, but some think that these commercial filters are not as effective as refillable filters that you fill with bone char yourself.  The difference lies in how the water travels through the filter — more on this below.
One might expect 90-100% fluoride removal with one gallon of bone char, in the first 800 gallons of water filtered.  Experiments showed 90% fluoride removal after 1,100 gallons of water filtered, and 70% fluoride removal after 1,500 gallons of water filtered.  Therefore, it might be a good idea to replace the gallon of bone char after around 1,000 gallons.

To source the bone char, you might start with contacting a company like Ebonex Corporation:, and ask for their 20 x 60 mesh size bone char, which DIYers have found useful for water filtration.  Feel free to review the data sheet for this bone char here.  I’m not sure if you can order directly from them or if they are only a wholesale distributor.  There may be many other companies supplying bone char.  The quality of the bone char could be differ depending on the temperature employed during charring.  Be sure to ask if temps in the range of 800 – 900 degrees C were used!

DIYers order a bulk bag of bone char, and use the char either in refillable ‘cartridges’ placed within filter housings, or within a Slow Sand Biofilter/Biochar Adsorber in the third tank.  These two ways to use biochar are described below.

2 ways to use these filtering media (biochar)

Multi-stage pressurized systems 

First, a low-tech DIY solution for under or over counter, using pre-made or refillable cartridges, explained here in the following video.
 The narrator of the video shows how to build a multi-stage system in the cheapest way possible.  You don’t have to follow his recommendations on the media filtration cartridges though.  Instead, you could select the following filters for your system:
  1. sedimentation filter
  2. bone char filter
  3. bone char filter
  4. activated carbon filter
He briefly reviews refillable cartridges in the video, but it is important to understand refillable cartridges function differently than the one-use pre-made filters.  In the one-use filters the water is forced through all sides of the filter, from the outside to the inside, and the water continues to the next stage from there.  In refillable cartridges, the water is forced through from bottom up, not the sides.  You can use these refillable canisters to experiment:  Refillable cartridges would be really useful if you are making your biochar from wood or other biomass to use in place of the commercially manufactured activated carbon filter, or if you are making biochar from bones (bone char) to filter out fluoride.  Bone char can also be purchased in bulk bags….and then you could fill the refillable cartridges.  Some think that refillable bone char filters are more effective, as a result of how the water travels through the filter in comparison with how the water flows through a commercially manufactured ‘one-time-use’ filter.  As mentioned above, in manufactured filters, the water is forced through the sides, which provides a low contact time with the bone char, and may not be forced uniformly through the entire filter.  In refillable cartridges, the water is instead forced through the length of the cartridge from bottom to top, which provides more contact time, which is what we need for fluoride reduction or removal.   
Remember, if you are making your own biochar, you must burn the material at 800-900 degrees C, in a low oxygen environment.
You can find out how to do this simply with these instructions.
In summary, you could explore the following options if using cartridges:
The 4″x20″ big blue is too heavy, it has to sit on floor or install on wall with 4 big screws and heavy duty bracket. Either case you need a hose from shower pipe to the big blue and an other hose from big blue to hand held shower head that you can move around. no height issue, it is located on floor corner of my shower, or it can be installed on the wall. you need two shower hoses.
there is mandatory range of water pressure we get at our house controlled by water company; It can not be outside that range. The shower heads are designed to control the flow of water for efficiency and minimizing water waste. 2 gallon per minute is a standard number we use for shower heads. and that is what I used in my email to keep things simple.
Most shower heads are around 1.7 to 2 gallon per minute. high water efficiency ones can be lower and really old shower heads can go as high as 2.5. I didn’t want to make the email too complicated, but flow can be anywhere from 1.2 to 2.5 gallon per minute with an average just under 2. most of population have shower heads ranging from 1.7 to 2 gallon per minute; I stayed on the conservative side (2).
If you want to be exact, you can use a bucket and measure the time it takes (in second) to fill the bucket using shower head. If volume of bucket in gallon is V then your flow rate is 60xV/S (S number of seconds took to fill it up). most home owners will end up around 1.7 to 2 gallon per minute.
Bone char recommendations:
  1. For shower I recommend using a 4”x20” big blue filter housing, it will hold around 1 gallon of bone char and can treat 800 to 1000 gallons of water.
It would last around 500 minutes of running water. So if each shower is 5 minutes, it would last you around 3 months (100 showers).
All I did was to remove my shower head from its hose, connected the existing hose to big blue housing inlet, using another shower hose connected the big blue outlet to shower head. You will need a few piping connections that local hardware store will provide. The problem is the large size of filter; keep in mind since contact time is 30s each time you open the water or adjust temperature, it takes 30 second for new water to come out.
  • For Drinking water: use three 2.5×10” hosing as minimum. The first two would be bone char and last one activated carbon. Some piping to install it under the counter. I would also add a valve and adjust the valve in a way that a one gallon container would take 30 seconds or more to fill (OR 8 seconds for a glass of water). This way you maintain the 30 second contact time and the filter would provide around 250~300 gallons of water before media need replacing.
  • I am also using a two 2.5×10” bone char filter for shower when I travel. It’s contact time is low due to high flow rate of shower however it is more practical to carry it with me when I travel. It would last around 20~25 showers 5 minutes each with around 90% Fluoride removal.
I recommend going to a store and seeing the filter housings first before ordering due to large size of the filters. If a company tried to sells you a smaller filter with bone char, don’t waist you money, it will not remove Fluoride effectively.
I guess every thing we use have some level of toxin in it. Any filter we use is made of plastic, steel or … our home water supply is copper piping that are solderd supposingly lead free.
Concerned about toxin? Yes. What can I do about it? Not much. Just try to get better quality stuff and make informed decisions hopping to minimize my exposure  to toxins 🙂

You can put bone char and activated carbon  in two layers in any container you want and run water through it assuming you go gravity fed with no pressure. However if you want to connect it to water line, then container need to be designed for tab water pressure and meet the related safety requirements. The are only a few types of pressurized mineral containers rated for drinking water in market:
1) the plastic housings as I mentioned in last email.
2) FRP tanks that normally used for whole house filters
3) stainless steel pressure vessels that are too expensive.
Biosand concept as you mentioned below will work perfectly for bone char. I will help you design it if you need any hand.

Gravity-fed systems

There are two main types of gravity fed systems:
    • Berkey type with pre-made activated carbon filters (made from coconut shell biomass)
    • DIY low-tech type
      • Slow Sand Biofilter
      • Slow Sand Biofilter/Biochar Adsorber (essentially a Slow Sand Biosand filter with an added step consisting of biochar).

The Aqueous Solutions website has many useful appropriate technology low-tech tutorials, including tutorials on how to build the slow sand/biochar adsorber biofilters!!!!

Little maintenance is required of these system.  The first tank in the system should be ‘cleaned’ 1-2 times per year, by closing off the tank, and opening the drain valve in the bottom and letting all the water out until it runs clearer.  Every year, the second tank in the system should be cleaned by stirring up the top of the sand layer until the water becomes turbid, and then opening the drain valve until only a little water is left. the Biochar in the third tank should be replaced at least every three years.  This can all be seen in this funny video:

The biggest pitfall in the slow sand systems is that the systems need fairly consistent use, especially when there is a lot of organic material in the water; this is because the biofilm that develops in/on the sand needs dissolved oxygen to keep it from going anaerobic.  If you leave the sand and the system for too long, you will need to run fresh water through the system to recondition the biofilm.  For this reason, building a very large system that is used by many people can be the best way to ensure the system will always be operating effectively, as there is less chance the system will go unused for even a day.

kearns design
Slow Sand Biofilter/Biohar Adsorber

The concrete rings used the video above from Pun Pun farm are made with a metal form and have a couple metal wire rings in the top and bottom.

A ferrocement tank would be even stronger than the concrete rings.  Some people build the tanks by laying fired brick, putting some rebar in between rows, and then plastering the inside with sand and cement, and then just cement and water.  If you want to be hardcore, you could make your own cement (portland) by heating limestone and clay.  I have no idea how that would work out.  The leaders of Aqueous Solutions have also made bamboo cement tanks….not sure what that means exactly.

The Aqueous Solutions website also has tutorials on how to build biochar gasifiers, so you an make your own biochar!  Traditional char was made using kilns like this, but unfortunately these don’t reach the 800-900 degree C needed to make the most optimal biochar, and the process takes a long time, from 5-10 days, to 1 day.

Screen Shot 2018-04-16 at 12.09.27 AM.png

So they feature another method (gasifier), which requires steel drums, as shown in this video, and the process only takes a couple hours.

I wish there was a more primitive method for making the biochar…not requiring barrels, like in the following two videos, but while the biochar made with these more simple methods are sufficient for agricultural use, they are not reliable for water filtration.  There is also a lot of ash mixed in there….just too hard to control the burn.

Let us stop polluting the water by learning how to live like villages again!  In the meantime, happy experimenting!

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