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What does an activated carbon water filter remove

What does activated carbon filters remove from tap water?

Activated carbon filters are pretty miraculous in terms of their abilities to remove contaminants, odor and bad taste from tap water. But how do they work and do you need one?

Here’s a simple overview of how active carbon filters work, what they remove and the limitations.

This blog is also summarised in a 2 min video. For details continue reading below.


How do activated carbon filters work?

What does activated carbon water filters remove?

Activated carbon filters sometimes referred to as charcoal filters contain small pieces of carbon, in granular or block form, that have been treated to be extremely porous. Just 4 grams of activated carbon has a surface area the equivalent of a football field (6400 sqm). It’s the massive surface area that allows active carbon filters to be very effective in adsorbing (essentially removing) contaminants and other substances.

When the water flows through active carbon filters the chemicals stick to the carbon resulting in purer water output. The effectiveness depends on the flow and temperature of the water. Therefore most smaller active carbon filters should be used with low pressure and cold water.

In addition to the surface area active carbon filters may have different capabilities in terms of the size of contaminants they remove. One factor is the quality of the activated carbon with coconut shells proven to have the best efficiency. Activated carbon can also be made of wood or coal and sold as granular activated carbon or carbon blocks.

Another factor is the size of the particles that the filter will allow through as this provides a second defense. Granular activated carbon (GAC) has no specific limit as the material is porous. Activated carbon in the form of carbon blocks on the other hand usually have a pore size of between 0.5 to 10 micron. The problem with the smallest sizes is that the water flow ends up being reduced as even the water particles struggle to get through. Therefore the typical carbon blocks are between 1-5 micron.

One of the top activated carbon manufacturers in the world is Swedish Jacobi used by TAPP Water. Jacobi produces the highest quality activated carbon such as Aquasorb based on sustainable and fair sourcing of coconuts. 

What does active carbon filters remove and reduce?

Activated carbon can be effective in reducing hundreds of substances including contaminants and other chemicals from the tap water. However, the most cited studies by EPA and NSF claim effective removal of between 60-80 chemicals, effective reduction of another 30 and moderate reduction for 22.

The range of effective removal is important and depends on the quality of the activated carbon used and in what form (GAC vs carbon block). Make sure to chose a filter that removes the contaminants of concern for your local tap water.

According to EPA (the Environmental Protection Agency in the United States) Activated Carbon is the only filter technology recommended to remove 

  • all 32 identified organic contaminants including THMs (by-products from chlorine). 
  • all 14 listed pesticides (this includes nitrates as well as pesticides such as glyphosate also referred to as roundup)
  • the 12 most common herbicides. 

These are the specific contaminants and other chemicals that charcoal filters remove.

Chlorine (Cl)

Most public tap water in Europe and North America is highly regulated, tested and certified for drinking. However, to make it safe, chlorine is added which may make it taste and smell bad. Activated Carbon filters are excellent at removing chlorine and related poor taste and odor. High quality activated carbon filters can remove 95% or more of the free chlorine.

For more details on this read about total and free chlorine

Chlorine should not be confused with Chloride which is a mineral combined by sodium and calcium. Chloride may actually increase slightly when the water is filtered with activated carbon.

Chlorine bi-products

The most common concern about tap water is by-products (VOCs) from chlorine such as THMs that are identified as potentially cancerous. Activated carbon is more effective than any other filter technology in removing these. According to EPA it removes the 32 most common chlorine by-products. The most common measured in tap water reports is total THMs.

Chloride (Cl-)

Chloride is a natural mineral that helps maintain proper blood volume, blood pressure, and pH of body fluids. However, excessive Chloride in water may cause a salty taste. Chloride is a natural component of tap water without any negative health aspects. It’s a part of the chlorination process of drinking water from harmful bacteria and viruses. It does not need to be filtered or removed but activated carbon typically reduces chloride by 50-70%. In exceptional cases chloride may actually increase.


Pesticides are substances that are meant to control pests, including weeds that end up in groundwater, lakes, rivers, the oceans and sometimes tap water despite treatment. Activated Carbon is tested to remove the 14 most common pesticides including Chlordane, Chlordecone (CLD/Kepone), Glyphosate (Round-up), Heptachlor, and Lindane. This also includes Nitrate (se below).


Herbicides also commonly known as weedkillers, are substances used to control unwanted plants. Activated Carbon is tested to remove 12 of the most common herbicides including 2,4-D and Atrazine.

Nitrate (NO32-)

Nitrate is one of the most important compounds for plants. It is a rich source of Nitrogen, which is essential for plant growth. Nitrate has no known harm-effect on adults unless it’s extremely high amounts. However, excessive Nitrate in water can cause Methemoglobinemia, or “blue baby” disease (Lack of oxygen). 

Nitrate in tap water primarily originates from fertilizers, septic systems, and manure storage or spreading operations. Activated carbon typically reduces nitrate by 50-70% depending on the quality of the filter.


PFAS/PFOS is a synthetic chemical used in e.g. fire-fighting foam, metal plating and stain repellents. Over the years it has ended up in the environment and drinking water sources with a couple of major incidents in North America and Europe. According to a 2002 study by the Environmental Directorate of the OECD “PFOS is persistent, bioaccumulative and toxic to mammalian species.” Activated Carbon has been found to effectively remove PFOS including PFAS, PFOA and PFNA. Read more about how to remove PFAS from tap water.

Phosphate (PO43-)

Phosphate, like nitrate, is essential for plant growth. Phosphate is a strong corrosion inhibitor. High concentration of Phosphate has not shown any health risks for humans. Public water systems (PWSs) commonly add phosphates to the drinking water to prevent the leaching of lead and copper from pipes and fixtures. High quality charcoal filters typically remove 70-90% of phosphates.

Lithium (Li+)

Lithium occurs naturally in drinking water at very low rates. Lithium has been found to have antidepressant properties and was used as an anti-depressant for many years. In higher doses Lithium has toxic effects on the thyroid gland and the kidneys. The thyroid toxicity, caused primarily by lithium’s interference with thyroid hormones’ release from the gland affects up to 19% of treated patients.

There is also a potentail link between Lithium in drinking water and increased risk of autism. 

Lithium can be found in continental brine water, geothermal waters, and oil-gas field brines. High quality activated carbon filters such as EcoPro by TAPP Water reduce 70-90%.


The ubiquitous use of pharmaceuticals has resulted in a relatively continuous discharge of pharmaceuticals and their metabolites into wastewater. Current observations suggest that it is very unlikely that exposure to very low levels of pharmaceuticals in drinking-water would result in appreciable adverse risks to human health, as concentrations of pharmaceuticals detected in drinking-water  are several orders of magnitude lower than the minimum therapeutic dose. Pharmaceuticals may be released into water sources in the effluents from poorly controlled manufacturing or production facilities, primarily those associated with generic medicines. High quality carbon block filters such as EcoPro remove 95% of pharmaceuticals.


Microplastics are the result of plastic waste in different kinds of sources. The precise effect of microplastics on human health is difficult to determine for a variety of reasons. There are many different types of plastics, as well as different chemical additives that may or may not be present. When plastic waste enters waterways, it does not degrade as natural materials do. Instead, exposure to the suns rays, reaction to oxygen, and degradation from physical elements such as waves and sand cause plastic debris to break down into tiny pieces. The smallest microplastics identified in public reports is 2.6 micron.

A 2 micron carbon block such as EcoPro removes all microplastics larger than than 2-microns.

Special Activated Carbon Filters

In addition to normal activated carbon, some filters either uses treated carbon such as catalytic activated carbon or ads other materials to improve the filtration.

In the case of EcoPro this means that the activated carbon block also removes/reduces: 

  • 95% or more of Chloramine
  • 95% Lead and Zinc (NSF-53 compliant)
  • 95% of Copper
  • 100% of Microplastics (thanks to the 1-2 micron carbon block)
  • 70% of heavy metals such as mercury
  • 70% of Nitrate
  • 70-90% of Lithium
  • 30-70% Arsenic and Asbestos
  • 80% of Limescale – new version of EcoPro cartridges.
  • 70% of Fluoride
  • Microbial cyst including giardia and cryptosporidium

By adding Ion Exchange and/or ultrafiltration layers it’s possible to remove further content including calcium (limescale) and pathogens (bacteria, coliform and viruses). TAPP Water provides an ultrafiltration filter for countries with non-potable water.

What Activated Carbon doesn’t filter

Despite the 80+ contaminants Activated Carbon filters there is also some materials it doesn’t remove

  • Healthy minerals such magnesium, potassium, sodium and Calcium  (this means TDS is generally not reduced with activated carbon)
  • Dissolved solids including minerals, salts or metals such as iron that are not considered contaminants
  • Some microbiological contaminants incl coliform, viruses and small bacteria
  • Inorganic contaminants such as arsenic and asbestos (only partially reduced)
  • Radionuclides although these are reduced

Activated carbon water filters generally do not reduce minerals or TDS (Total Dissolved Solids) which is a common measure used by water filter sales people. Read our separate blog about TDS and minerals in tap water. Read more about TDS and minerals in tap water.

Microbiological contaminants

This is one of the most common drinking water issues in countries with poor infrastructure. Especially for waterborne gastrointestinal diseases (e.g. diarrhea that visitors not used to the local water get).

Natural water represents an adequate environment for bacteria and viruses to grow. Viruses are the smallest form of microorganisms capable of causing disease, particularly those of a fecal origin infectious to humans by waterborne transmission; bacteria are typically single-celled microorganisms that can also cause health problems in humans, animals or plants.

Generally the chlorine in tap water will kill all bacteria and viruses which is why filtering of these substances is not necessary for public water in Europe and North America. Activated carbon filters on their own are generally not sufficient to remove such contaminants.

Activated Carbon filters do not filter/remove corona viruses that may cause Covid19. But don’t worry, corona viruses have never been found in disinfected tap water. Read more about how to protect yourself from Coronaviruses and Covid19.


Common in some places where the groundwater has been contaminated. Activated Carbon removes 30-70% of arsenic but is not sufficient in places where this is highlighted as a real problem.

If your local water contains one or more of these substances then you should ensure that the filter reduces them to a safe level. Most of the time this means combining activated carbon with other types of filters such as Ion Exchange. Read more about the best filtering technologies.

Conclusion about activated carbon filters

Activated Carbon is an exceptional material and technology for water filtering and solves many issues but not all. 

  • Make sure you understand the limitations of activated carbon and chose a filter based on your specific needs 
  • High quality activated carbon filters such as ta use treated materials to enhance the filtering efficiency including lead, other heavy metals, microplastics and some bacteria
  • Activated carbon filters retain the healthy minerals and therefore generally do not reduce the TDS in tap water unless combined with other filtration technologies
  • Activated carbon or charcoal filters are also used as one of the stages in most Reverse Osmosis (RO), whole house filters, UV filters and other filter technologies
  • If you are looking for an affordable high quality water activated carbon water filter then try EcoPro

In case of uncertainty about which contaminants are filtered feel free to contact us on [email protected]

Read about TAPP Water in comparison with other water filters such as Brita, PUR and Culligan.


Originally posted 15 January 2018. Last updated 13 April 2023.

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40 thoughts on “What does activated carbon filters remove from tap water?”

  1. i am really interested with this artecal .
    i have a research in my university about how to remove bacteria (E coli)from water using avtivative carbon filter. wold you help me this research

  2. I live near an asphalt plant . I’m sure that their cleaning processes end up in a water source that I might have to use as an emergency back – up . Can activated carbon remove the chemicals that they use to make their product ?

    1. Hi Gerald, the best way to proceed in special cases like yours would be to make a lab test of your tap water to identify what chemicals are in it. Try to do it with an independent party (not a filter company) for extra objectivity. Once you know the list of chemicals it will be easier to identify the right filter for your home! Hope this helps. Best, the TAPP team

  3. Hello Erik,
    I would appreciate your comments on this published paper, from 1990 in “Environmental Technology”, that I found, that states MX can be removed from drinking water by using a GAC filter. So far, this is the only online source I have found stating that the GAC filer is effective in removing MX from drinking water.


    Thanks for your help, in helping me understand the truth about MX.

  4. Two questions for you 🙂 I’m thinking of buying one because I just moved here and the water here in Barcelona smells like a swimming pool 🙂 And you have a local product. But I have 2 questions:

    – Does it also remove limescale? I don’t know the exact term for this but I mean the stuff that causes water ‘hardness’ and clogs up my coffee machine 🙂
    – Is the activated carbon itself safe to ingest? I assume some of it will make it into the water?

    1. Hi Robert,

      Thank you for reaching out! Here are the answers to your questions:
      – Limescale: the filter does not filter out limescale, since activated carbon lets the minerals remain (including calcium, potassium, etc.). However, you will notice by using it in your coffee machine or kettle that the clogging does not occur at such an extent since there are other factors – not only limescale – that may be causing it.
      – Safety of activated carbon: the activated carbon is safe to ingest although if it does happen that it leaches, it would be in very very small quantities. Activated carbon is used in toothpastes, soaps and even sold in bulk to ingest due to its purifying and adsorption properties.
      Let us know if you have any further questions! And remember you can always come to try it at our offices or to buy it and then give it back if you are not satisfied.

      The TAPP Water team

      1. Hello we just installed a polyphospate crystal filter cartridge to reduce the huge amount of carbinate deposits that builds up from our water out of a limestone mountain. Although the water tastes much softer I do not feel well drinking it. I have learnt from experience to take act on my highly tuned senses.
        Will a 1 micron activated filter remove any residual polyphospates from my drinking water otherwise I will need to bypass the polyphospate filter for my drinking water.

  5. -would be nice to know if it also removes medical residues for example from birth control pills, estrogen is in small amounts in water also “happy pill” residues for example

    1. Thank you for your question Adam!

      Based on tests performed on the type of activated carbon block used in TAPP 2 pharmaceuticals are reduced by 95% or more. This includes:
      – Hormones: prednisone, prednisolone, progesterone, testosterone and cortisol
      – Antibiotics: ciprofloxacin, used to prevent certain infections caused by bacteria, as well as sulfamethoxazole and trimethoprim, which are used to treat a wide variety of bacterial infections including pneumonia, and urinary tract and intestinal infections
      – Antidepressants: fluoxetine, prescribed to treat a variety of conditions, including depression and other mental/mood disorders
      – Anti-anxiety medication: meprobamate, a treatment used to relieve nervousness or tension that exceeds stress of everyday life
      – Painkillers: ibuprofen and naproxen

      The TAPP Water team

    1. Hi John,
      Thank you for your question.
      Small molecules like O2, CO2, or N2 are not large enough for an activated carbon filter to remove, so you should be safe!
      The TAPP Water Team

  6. That’s interesting that chemicals will stick to the carbon as the water passes through it. I would want to make sure that I get everything harmful out of my drinking water, so that sounds good. I would think that would make your water taste better as well. so I might have to take a look at a filter for my house.

  7. Activated carbon indeed is one of the best solution for treating contaminated water, as I read in a blog by Grand View Research titled ‘How Active Is The Activated Carbon Market?’, which mentioned water purification as the primary application. What I did not know is the sheer enormity of the surface area of such small amount of the carbon. However, I also read somewhere that it can cause clogging in plants, so how can this be avoided or circumvented?

    1. Not entirely sure what you mean. You mean in organic growing plants or water plants? Generally the activated carbon should not be allowed to leech into the tap water.

  8. Very informative article. Just one question?
    Is it possible to mix activated carbon with ion exchanger in one tank to both filter the water from contaminant and reduce water conductivity? Or they must be in two stages and tanks? – I use mixed ion exchanger and I am going to use it for Wire-Cut EDM Machine, I have separate ion exchanger chamber but water conductivity is still high –

  9. I saw in the article how only special certified carbon filters remove lead. Do regular uncertified activated carbon filters at least reduce any lead or heavy metals?

    1. Activated carbon on it’s own may reduce some heavy metals by 50% or more. It depends on the material, mix, amount, throughput and many other factors though. This is why you need to ask for the product to have been independently tested and certified.

      The TAPP Water Team

    1. Yes. Activated charcoal and activated carbon is the same thing. Although charcoal is primarily used for wood based activated carbon rather than coconut shells used by TAPP Water.

      The TAPP Water Team

  10. My in laws have a new Quooker boiling water tap with the added function of an activated carbon filter for filtered drinking water. I tested the outside normal tap water and it registered 330ppm using a TDS meter. The filtered water from the Quooker filtered water function gave a reading of 320ppm. I have a 5 stage reverse osmosis system and my outside tap is 340ppm and my RO water is down to 25ppm. So mine works very well and has an inline alkaline filter too. Can I safely say the Quooker is simply doing nothing to filter water to drink?

    1. Hi Carlos,

      Thanks for your question. As per our other article on TDS, this is not a good indicator of water quality. TDS is generally an indication of the amount of healthy minerals including calcium, magnesium and potassium. Therefore high TDS can be a good indicator.

      Reverse Osmosis filters generally remove most of the minerals. Some of them later add it back to improve the taste and health aspects of the tap water.

      The only reason to use a RO filter is basically if you have well water or live in an area where the public tap water is not potable/drinkable.

      The Quooker product seems like very expensive for what it does but as long as your parents are happy with the taste.

      The TAPP Water Team

  11. Hello,
    First off, thank you for all of this excellent information. We use a quick twist carbon block filter in our home for our drinking water and it has always worked well. Yesterday, we replaced the old filter with a new one and now the drinking water tastes like it has chlorine in it. Is there any chance, this filter is not working properly? If so, what could have happened?
    Thank you in advance for any input you might have.
    Brian Peterson

    1. Apologies for slow respose. We have had this reported by a few customers. Unfortunately we don’t know the reason but replacing the cartridges worked in all cases. Our recommendation would be to request a replacement cartridge from our support team. Please e-mail [email protected]

      The TAPP Water Team

  12. I need to know is it a good practice to use two water filters one Reverse Osmosis and another Carbon Block Filter? Some RO systems have the CB filter in them and some don’t have? I have no hassle of maintenance problem, I can deal with it but I don’t want to compromise on health of my family

    1. Our 5-stage carbon block filters do remove 90% or more of phosphorous. Based on our experience activated carbon will adsorb phosphorous but we don’t know the efficiency of the PUR filters. You need to ask PUR about.

      The TAPP Water Team

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