Make homemade ‘charred’ biomass. Filter out industrial and agricultural chemicals in your water.

Many wonderful people have been addressing the issue and lack of healthy water in communities around the world for many years through non-profits and NGOs.  Although these efforts address the most acute threat – microbiological organisms which quickly cause illness and death, they have not addressed the equally lethal contaminants that lead to chronic illness and slower death – namely industrial chemicals, heavy metals, and agricultural chemicals, also known as organic contaminants.  If it were not for these chemicals, filtering water through clay would be sufficient to remove the microbiologicals, and wouldn’t require energy during filtration.  Even boiling water would be sufficient to kill pathogens, although boiling does not remove, and actually concentrates the endotoxins from the pathogens.  But as things stand today, removing just microbiologicals is no longer sufficient to prevent disease.

I recently learned about one organization addressing BOTH issues — the organization is called Aqueous Solutions, and was founded by Josh Kearns.  He has created a website with videos and tutorials so that we can all benefit from the knowledge his scientific research team and development team have amassed and tested.  Josh Kearns explains in this YouTube video how his team started with the biosand filter, and expanded the concept to effectively filter out heavy metals and other organic contaminants as well as microbiologicals.  Their knowledge is critical to the improvement in health in developing nation communities, who have no municipal water purification or water treatment systems in place, and yet are often the ones literally living downstream from the factory making the consumer goods for first world nations, and dumping all the chemicals into the river the locals use to survive.

Although I have access to treated water from municipal treatment plants in my city, there is a need for us to learn these methods as well, particularly as they could eliminate the chemicals that still remain in the treated water, and are sometimes added during the treatment process, such as aluminum salts, in addition to the fluoride which is added to supposedly ‘medicate’ the public’s ailing teeth.   We need to bring water purification back home, and interrupt yet another way that we continue to pollute our natural resources, and ourselves.

There are five main ways to treat water, as shown in the list below, but Josh Kearns focuses on #4: filtering media – in gravity-fed systems.  In this post we will discuss both multi-stage pressurized systems and gravity fed systems.

  1. Distillation
  2. Deionizer, with or without exchange resin
  3. Reverse Osmosis
  4. Filtering media – used in multi-stage pressurized systems OR gravity-fed systems
    • Ceramic
    • Activated carbon or biochar
    • Sand
  5. ***Harvesting and filtering rainwater

Before we get into the details, it is important that before you select and build any water treatment system, it is important to identify which contaminants reside in your water.  This knowledge will allow you to target a solution that effectively cleans your water.  For example, if you are drawing from a well, you may not have to worry about filtering fluoride.   Read this post first to learn how to assess your water. 

Short version: almost all water contaminants can be filtered with activated carbon or biochar made from the common coconut shells, and ALL contaminants (including fluoride) can be filtered with activated carbon or biochar made from bones.  The easiest way for those of us in urban or suburban areas to use commercially manufactured activated carbon filtes is in an under counter multi-stage system.  The second easiest way is to use commercially manufactured filters in stacked containers, like the Berkey system, and the most ecologically friendly way to use these materials is in a Slow Sand Biofilter/Biochar Adsorber, as shown in the following hilarious video from the PunPun farm in Thailand.  


Carbon (Activated)

charCarbon (which is essentially burned material, such as wood or other biomass like coconut shell) has been used as a water filtration media for ages.  However, we are regaining some of this knowledge and research continues.  Carbon is simply the result of biomass (like wood, or coconut shells) that has been burned at high temperatures in a low-oxygen environment.  Commercial manufacturers grind the burned biomass into fine powder, and through proprietary processes, form the powder into cylindrical filters.  The best carbon filters available from manufacturers like Berkey are ‘activated carbon from coconut shells.’

There are several carbon filter manufacturers.  I will focus on Berkey (New Millennium Concepts), because I have personally used their carbon filters.

Screen Shot 2018-04-14 at 11.58.10 PM

Although these coconut-shell activated carbon filters remove bacteria, viruses, and numerous heavy metals (see their test results), they DO NOT filter out fluoride after the first hundred gallons or less, as Berkey explains on their website, because ‘filtration elements that reduce fluoride begin to lose that ability quickly,‘ and that ‘it takes a very large amount of media to reduce small amounts of Fluoride.  Therefore, there is not enough media in filters to reduce fluoride effectively over the long term.


PF-2 Berkey Filter – Removes Fuoride? Or is there an alternative?

The PF-2 filter that you can purchase/add to your Berkey system, designed to filter out fluoride and arsenic, consists of aluminum oxide, which is one of the very few materials that can remove fluoride.  However, this aluminum filter may release aluminum into water that you’ve worked so hard to gravity filter in the first place.  Berkey’s knowledge base says:

“Pure aluminum is water-soluble, it is highly reactive and it is associated with negative health effects.  By contrast, aluminum oxide [that we use as the media to filter out aluminum in the PF-2 filter] is not water-soluble; it is inert, is very stable, and is not associated with negative health effects.”  

While aluminum oxide filters may be effective in reducing fluoride for a limited time, and in limited situations (see below for limitations related to water pH),  peer-reviewed scientific study is needed to convince me that aluminum is not being released from this filter.

Due to the way activated alumina is made, the PF-2 filters comes with a lot of fine dust, and I’m guessing that is why Berkey directs consumers to ‘prime’ the filter for 10 minutes, or until the water coming out of the filter runs ‘clear.’  It is common industry practice to provide unwashed media (activated alumina) in the filter, assuming the consumer will following the ‘priming’ instructions.  The water that comes out has a milky color, which is a result of the activated alumina being washed out with the water; however, just because the water looks like it is running clear after several minutes, doesn’t mean it is actually free of activated alumina dust.  It just means that you can no longer detect the dust with the naked human eye.
Even after some use,  more dust could be released, when the filters is moved, or there is a change in water flow, etc, and the dust ends up in the filtered water.
I consulted aluminum ecotoxicologist Christopher Exley regarding alumina, and he advised that we should be avoid filters with activated alumina, until studies demonstrate the safety of alumina in their various product applications.  If fluoride levels are below 0.5 ppm (mg/L)  in the water, I believe the fluoride may be less of a concern than the potential alumina released from the PF-2 Berkey filters.

However, if the pH of the water is 7 or higher, the PF-2 filters won’t work anyway!!!  This limitation is stated on the Berkey website, but I feel is almost always missed by purchasers.  It actually seems a tad scummy that Berkey doesn’t put this limitation in bold and underlined verbiage on the PF-2 product page.  The median pH of my city’s water was 7.26 in 2016 — so, the PF-2 filter wouldn’t work for me.  Plus, they must be replaced much more often than the black carbon filter, which is good for 3,000 gallons.  Remember, ‘it takes a very large amount of media to reduce small amounts of Fluoride.  Therefore, there is not enough media in filters to reduce fluoride effectively over the long term.


AS AN ALTERNATIVE, CONSIDER USING BIOCHAR MADE FROM BONES INSTEAD OF COCONUT SHELL OR OTHER WOODY BIOMASS TO REMOVE FLUORIDE.  Read about how to do this in the post called: “Make your own fluoride filter, from ‘charred’ bones – BIOCHAR!”





Before buying a Berkey water filter, you should also consider that the water must be used up/moved/added at least every three days, to inhibit the growth of bacteria in the virtually enclosed space of the system, and that the system should be cleaned with water and vinegar once a month.  That means if you leave for vacation for a few days, you have to take some extra time to care for your filters.  The filters contain silver to prevent bacterial growth within the actual filters themselves, which is good, but saddens me.  We are benefiting while the poor people that work in the silver mines are working in horrendous conditions, and die very young from health problems and diseases resulting from their work in the mines.  But this is the case with all metals – gold, silver, zinc, etc.



Biochar is made differently than activated carbon; however, it performs similarly.  It is essentially biomass burned at 900 degrees F in a low-oxygen environment.  Different biomass could yield different results; for example, biochar made from bones, like this bone char 20×60 mesh from Ebonex has the ability to filter out fluoride, whereas biochar made from other things like coconut shells do not remove fluoride.  Bone char can be bought in bulk from a variety of corporations for use in refillable cartridges meant for use in under counter multi stage filter systems, or for use in gravity fed filter systems, but one should ask for exact process spec regarding the char process, so you can ensure that the char was created at 900 degrees C in a low oxygen environment for best filtering results.  To learn more about biochar made from bones specifically, read the post called: Make your own fluoride filter, from bones!






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. 

Carbon has been used as a water filtration media for ages.  However, we are regaining some of this knowledge and research continues.

2 ways to use these filtering media materials

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. char filter made from bones
  3. char filter made from bones
  4. char filter made from coconut shell or other biomass
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.  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.

Gravity-fed systems

There are two main types of gravity fed systems:
    1. Berkey type with pre-made activated carbon filters (made from coconut shell biomass)
    2. DIY low-tech type
      1. Slow Sand Biofilter
      2. Slow Sand Biofilter/Biochar Adsorber (essentially a Slow Sand Biosand filter with an added step consisting of biochar).
    1. Aqueous Solutions – Biochar Workshop Thailand from Darcy Muenchrath on Vimeo.

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.

To learn about all methods used to filter water, read this post called: Drinking Water: Solutions & Filters.
To learn more about biochar, specifically biochar made from bones to remove fluoride from water, read the post called: Make your own fluoride filter, from bones!


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