Drinking Water: Solutions & Filters

Before you read about the water improvement solutions listed below, it is important to know which contaminants reside in your water.  This knowledge will allow you to target a solution that effectively cleans your water.  Every water source is very different — different in pH, and in the contaminants present.   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 these filtering materials is in an under counter multi-stage system.  The second easiest way is to use these materials in a premade gravity system such as the Berkey system, and the hardest and 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.  You can find more information about gravity-fed systems using manufactured activated carbon filters in under counter or Berkey-like gravity fed systems toward bottom of this post, as well as more information about how to build the Slow Sand Biofilter/Biochar Adsorber.  Although these methods, especially the Adsorber are my favorite and preferred methods, in this post I cover all the methods I learned about, including reverse osmosis, deionizers, etc. 


Some contaminants, such as BPA (50muM), can be almost completely removed within 24 h when the ratio of whole plant weight to the water volume was set up at 1 g to 25 ml, according to this study.

Most people are familiar with the concept of boiling water or adding chlorine to water to purify it, but these methods are inadequate in modern times – they do not remove organic contaminants (chemicals) or microbiological endotoxins.   There are more sophisticated methods to purify water – which I was surprised to discover!   In this post, I will share what I’ve learned about each method, saving my favorite for last (filtering media used in multi-stage pressurized systems or preferably, gravity-fed systems.  The methods are listed in order of maintenance or effort required, from the least maintenance, to the most maintenance.  As is often the case, the most environmentally friendly options require a little more maintenance and effort.

  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

I’ve consulted with others to learn about these methods, and I’m pleased to share my personal experience with activated carbon filtering media as well.  After you become familiar with the five basic methods and their variations, you can select the method that seems right for you, and research further to make sure that the chosen method will filter out the specific contaminants present in your water.


aquanui#1 – Distillation

While distillers can be designed in a way that makes them effective in removing all contaminants, including fluoride, I don’t believe they are the most environmentally-friendly option, due to pollution caused by the mining and processing of the metal containers and components, as well as pollution and expense caused by required ongoing electrical energy costs.
However, if you have an abundance of money, live in a country where energy is cheap and reliable, and need a water system that requires the least maintenance, distillation may be a good option.  The 8-gallon unit produces 1 gallon in 3 hours.  Learn more about distillation by clicking here.

A good distiller does require some cleaning and the carbon filter may need to be replaced every 3 months, which totals $40/year. 

The AquaNui units use 3 kilowatt hours per gallon distilled.  If you distilled 4 gallons per day, electricity costs would total $25 per month if you used it during peak energy hours, and it would cost $16 per month during non-peak energy hours.
With filters and energy, the system might cost $232 – $340 per year.

#2 – Deionizer, with exchange resin

Deionizing typically involves two steps – the first step is the removal of all positive metallic ions/replacing them with hydrogen ions, resulting in acidic water.  This is similar to the process employed in household water softeners, but in the softening process only the calcium and magnesium ions are removed, and they are replaced with sodium ions rather than hydrogen.   These systems often have a sediment filter and an ultraviolet lamp in addition to the membrane and resins.  If the deionizer doesn’t use an ion exchange resin, it will not remove the fluoride.


In the second step, the water flows through an anion exchange material.  The negative ions (including fluoride) are absorbed into the anion, and hydroxyl anions are released and take the place of the negative ions.   The resulting water contains positive hydrogen ions from the first step, and negative hydroxyl ions released in the second step.  I don’t fully understand this technology, and I’m not sure if all deionizers are using the exchange resin needed to remove fluoride.

The distinct advantage of the deionizer with ion exchange resin, is that when either resin is saturated, ions will appear in the collected water, which will immediately and dramatically increase the electrical conductivity of the solution and thus be readily detectable by a very cheap monitoring system.” – The Fluoride Action Network

linxI’ve read that deionizers with ion exchange resins are less wasteful of both energy and water, compared with reverse osmosis.

There are variations of this technology, such as the systems sold by LINX.  The LINX system uses a two-layer membrane containing ion exchange resin – a cation resin on one side and anion resin on the other.  Electricity efficiently binds contaminants into the membrane.  When the membrane becomes saturated with contaminants (about every 12 liters/3 gallons of treated water for LINX 140, and about 6 liters/1.5 gallons for the LINX 160) the system regenerates, during which time the voltage polarity is reversed and the contaminants are expelled from the membrane and flushed out, leaving the membrane prepared for more deionization.

The sediment and other filters should be replaced annually, and the cartridges hould be replaced every 2-4 years, depending on family size.  You would have to pay for the filters/cartridges as well as service (the company visits your home to replace).  How much water one can draw at one time is determined by the size of the storage tank for the LINX 160 and 140T systems. For the LINX 140 (tank-less) system up to 3 gallons (12 liters) of water is available prior to regeneration.

I’m not sure about the costs on other deionizer systems, but LINX filter should last 2-4 years, depending on family size, etc.  The replacement filters cost $100-$250.  LINX systems use 0.2 kWh per gallon.  If you deionized 4 gallons per day, electricity costs would total $2 per month if you used it during peak energy hours, and it would cost $1 per month during non-peak energy hours.

With filters and energy, the system might cost $126 – $195 per year.


#3 – Reverse Osmosis

“In an R-O system, the water is forced at high pressure through a semi-permeable membrane.  The fluoride ions, with a sheath of water molecules, are too large to pass through the small pores in the membrane and only the water can get through. Thus virtually pure water is squeezed through the membrane.” – The Fluoride Action Network

These systems typically include a sediment filter, an activated carbon filter, and an ultraviolet lamp in addition to the reverse osmosis semi-permeable membrane.

“Waterite” (https://www.waterite.com/) may have quality RO membranes.  You might be able to find them for $200~$300 or even less.

RO membranes will become damaged if exposed to clorine in tap water! 
The pre filtration cartridges are designed to remove chlorine.  So if cartridges are not replaced regularly as required, the membrane becomes damaged and fluoride leaks through. 
The first year using the Waterite brand reverse osmosis system, users measured no detectable fluoride.  At 2 years they saw around 0.05 PPM of fluoride (~95% fluoride reduction).  Even with proper maintenance, an RO membrane has a life of around 3 to 5 years depending on water quality and use.  Replacing the membrane is also required every few years.

FAN shares that Dr. Richard Sauerheber, a chemistry professor in San Diego, warns that not all reverse osmosis systems achieve satisfactory fluoride-filtering results.  Sauerheber tested the effectiveness of various RO systems and found that the efficiency of removing fluoride varied significantly among systems, and seemed to depend, in part, on the flow rate of the water.  In others, the greater the flow of water through the system, the less effective they were at removing fluoride.

In a recent blog post from BerkeyWater.com, Reverse Osmosis is explained in away that is easy to understand:

Osmosis is the “tendency of water to flow from a hypotonic solution (low concentration of dissolved substances) to hypertonic solution (higher concentration of dissolved substances) across a semipermeable membrane.”1

Think of a tank of water with two chambers. One chamber has a low level of dissolved substances (salt, bacteria, or contaminants), while the other chamber has a high level of dissolved substances. Water would naturally flow through a semipermeable membrane toward the chamber with the higher level of dissolved substances in order to even out the concentrations between the two chambers.

Reverse Osmosis pressurizes the solution with the higher level of dissolved substances in order to reverse the natural flow of osmosis. It forces water to move toward the chamber with the lower level of dissolved substances, resulting in filtered water accumulating in the second chamber.

Bacteria Reduction and Tank Colonization

If the bladder tank is not sterilized with chlorine or something else on a regular basis, it could become a source for bacteriological contamination. Note that the carcasses of the dead bacteria may remain within the bladder tank (the filtered drinking water) with a Reverse Osmosis system.


#4 – Filtering media – used in Multi-stage pressurized systems OR Gravity-fed systems

  • Ceramic
  • Cob / ceramic combo
  • Carbon (activated) or biochar
  • Carbon (activated) / ceramic combo
  • Aluminum
  • Sand



Potters for Peace empowers local ceramicists in various countries to make low-cost ceramic water filters, sometimes called Filtron filters.  Potters for Peace also focus almost solely on microbiologicals, although a researcher tested the ceramic-filtered water for several metallic elements (aluminium, antimony, arsenic, barium, copper, manganese, silicon and silver), which were “found in higher concentrations in the effluent [filtered water] than in the influent ”  The concentrations of these metallic elements varied based on the location in which the clay was harvested and shaped into filters, as the type of clay differs location to location, as well as the level of types of industrial, agricultural and household pollution.  Some of the metallic element concentrations found in the effluent differed as a result of time the filter had been in use.


Cob / Ceramic Combo

Another interesting idea, for which I don’t see supporting lab testing, is the high temp baked ‘cob’ pot filter (mixture of clay and biomass – in this case, rice husks), baked for a day at 1472 degrees F.   The page says that the cob/ceramic combo filter can remove pesticides and heavy metal by up to 99%, but we don’t know how stringent or lax the testing criteria was, whereas Josh Kearns stated that they used some of the most difficult-to-remove as their filtering success criteria.  I think this is a really interesting idea nonetheless.





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.  They 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 the Berkey black carbon component filters out bacteria, viruses, and numerous heavy metals (see their test results), it cannot filter out fluoride after the first hundred gallons or so 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.

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.




I’ve been a huge fan of the CAWST organization, as their low-tech DIY filters can be built by anyone, in any country, and effectively filter out bacteria and other pathogenic organisms (microbiologicals); however the organization doesn’t necessarily focus on filtering out other contaminants, such as pharmaceutical drugs, agricultural pesticides, fungicides, herbicides, etc, fluoride, and heavy metals like aluminum and lead (corroding from the inside of the lead pipes bringing the water from the treatment plants or community well, to our faucets).  This led me to one of Josh Kearn’s talks on YouTube, which he explains how he takes the biosand filter, and expands the concept, to effectively filter out microbiologicals as well as heavy metals and other organic contaminants.

I’ve been a huge fan of the CAWST organization, as their low-tech DIY filters can be built by anyone, in any country, and effectively filter out bacteria and other pathogenic organisms (microbiologicals); however the organization doesn’t necessarily focus on filtering out other contaminants, such as pharmaceutical drugs, agricultural pesticides, fungicides, herbicides, etc, fluoride, and heavy metals like aluminum and lead (corroding from the inside of the lead pipes bringing the water from the treatment plants or community well, to our faucets).  This led me to one of Josh Kearn’s talks on YouTube, which he explains how he takes the biosand filter, and expands the concept, to effectively filter out microbiologicals as well as heavy metals and other organic contaminants.  More information on his design of a biosand filter which incorporates biochar can be found farther below in this post.  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.

Carbon (activated) / ceramic combo

Consumers can purchase handheld / hand-pump ceramic filters from https://www.msrgear.com/miniworks-ex-microfilter.   This filter cannot remove viruses.  Since it has a carbon layer, I’m not sure why this is the case….


The PF-2 filter that you can purchase/add to your Berkey system is designed to filter out fluoride and arsenic, via the aluminum oxide media it contains, which 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.  I consulted aluminum ecotoxicologist Christopher Exley regarding alumina, and he advised that we should be avoid filters with activated alumina (which is simply aluminum), until studies demonstrate the safety of alumina in their various product applications.  Fluoride is damaging in the body, and I’ve read that it can aid aluminum in its ability to cross from the gut to the blood, but I must weigh pros and cons.  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 aluminum 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.


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. 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: https://www.amazon.com/dp/B00JFB0CF8/?ref=exp_inf_pl_designedbyinstinct.  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.

Harvesting and filtering rainwater

Rainwater Harvesting + Carbon Filtration

For those who do not have access to abundant or cheap energy may need to find a different method of water purification.  For example, the load of this distiller may be too much for those who have off-grid solar systems, but I don’t have much expertise on this topic, except to state that the current solar inverters used in solar off-grid energy systems produce incredible amount of electromagnetic interference, which is damaging to the cells of our body.  I truly hope that the leaders in the industry begin to recognize the negative health impact of the current inverters – I know it is possible to create a “clean” inverter.

For alternatives, I’ve thought about installing a rain harvesting system, which should theoretically have fluoride levels as low as spring water.  At that point, the rainwater would be filtered through a carbon filter to remove any organic contaminants that come down with the rain, like glyphosate, and any heavy metals leached from your roof materials.  The low pH of ‘acid rain’, which you could see in your harvested rainwater could be an issue for the integrity of tooth enamel, as can any acidic foods, such as soda or lemon juice.

Pure water has a pH of 7.0 (neutral); however, natural, unpolluted rainwater actually has a pH of about 5.6 (acidic).  In some areas with acid rain, the pH of rainwater can be as low as 3.0, or even 1.8 which was measured in West Coast fog.

I was shocked when I learned about acid rain.  I was super shocked when I learned that various fisheries consider it standard practice to dump approx. hundreds of tons of limestone sand into the waterways each year (totaling $350,000 in some states), in order to neutralize the pH in the acid-rain filled bodies of water.   They do this to protect the ecosystem, as certain species of fish and other wildlife cannot survive in water that is too acidic.

To test the pH of your rainwater, you can buy pH strips from chemical supply stores, or aquatic life stores, etc.  I believe you can also determine the pH by ordering a water sample test using the company listed previously in this post.

To raise the pH, some people add 1-2 boxes of baking soda to their rainwater tank every 2-4 weeks.  Others suggest adding calcium carbonate granules, available from chemical supply companies.

Filters (and Fluoride)

Many of filters or filtering media work extremely well for almost all contaminants; however, most of them cannot effectively filter out fluoride, and if they can, you must replace the filter and/or other components regularly.

The first line of defense regarding fluoride should be activism – we should all fight to put an end to the addition of fluoride to our drinking water.  Read the post about fluoride for tips on how to begin this process.

If you live in a community that fluoridates its water supply, there are several options to decrease the levels of fluoride.  If you have access to a free source of fluoride-free spring water – you are very lucky (most spring water contains very low levels of fluoride (generally less than 0.1 ppm))!

Distillation equipment can be very expensive, and because of this, many people turn to less expensive methods, like reverse osmosis or biochar made from bones.

Final Notes  

It is interesting to consider his work, and also consider ways that other cultures have filtered water — like these simple pieces of char wood sold by www.LifeWithoutPlastic.com for the purpose of filtration.   The product page states:

The Japanese have been using Binchotan charcoal for centuries to purify water. No need for the disposable plastic casing typically used to hold charcoal granules as the charcoal stick is a natural absorber of impurities.

One stick of the small size Binchotan charcoal for bottle lasts up to four months, purifying approximately 1 litre / 4 cups of water per day. Just let the stick sit in the water for about 1 hour before using.

Binchotan charcoal is a unique charcoal exclusive to the forests of Wakayama, a province in southern Japan. The branches of holm oak trees are sustainably harvested then slowly fired in traditional kiln ovens over many days. Binchotan charcoal sticks naturally absorb toxins such as chlorine, lead, mercury, cadmium and copper from tap water and impart good minerals such as calcium, potassium, magnesium and phosphates to water.

Care and use: It is recommended that the stick be boiled in a shallow pan of water for 10 minutes every month or so to keep the exterior pores open and make it last longer.  After four months, boil the charcoal stick again. If you don’t see a profusion of bubbles circulating around the charcoal stick when it is returned to the water bottle and water is added, the stick has reached its capacity to absorb toxins. At that point it is ready to be composted in the garden or used as an odor absorber in the fridge.

It seems that regardless of my desire to live simply and without what seems like an endless list of manufactured gadgets and devices, including items such as the Berkey filtering system components to filter water.  The incredible level of pollution we’ve released into our environment and continue to release, requires that we not only treat water city-wide, but that we also treat the water when it comes out of the faucet in our home.   No substance we use remains contained in any system….it always finds its way into the air and water we all use.  This is a good reminder to strive toward natural materials found above ground or in shallowly dug pits, and the least processed, such as wood, stone, natural fibers, clay, and sand vs. metals and plastics.

2 thoughts on “Drinking Water: Solutions & Filters

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