What Do Activated Carbon Filters Remove From Tap Water?

What Do Activated Carbon Filters Remove From Tap Water

Activated carbon filters are used because they do an excellent job of removing contaminants, odor, and bad taste from tap water.

They are often found in refrigerators and water pitchers, and they can absorb natural organic compounds, taste and odor compounds, and synthetic organic chemicals.

When these compounds flow through a carbon filter, the chemicals and compounds stick to the carbon and the resulting water is more pure.

What Is an Activated Carbon Filter?

Cross-section of a water filter

An activated carbon filter is a filtration method that uses a bed of activated carbon to remove impurities from tap water by absorbing them.

The impurities, which can be organic compounds, taste and odor compounds, or chemicals, are trapped in the pores of the carbon filter.

It is one of the most powerful absorbents out there, and when it is activated, it has a slightly positive charge to it, which attracts even more chemicals and other impurities than if it were not activated.

What Types of Activated Carbon Filters Are There?

Most activated carbon filters that are used in homes for water treatment are either granular activated carbon (GAC) or powdered block carbon. They both do a good job, but carbon block filters tend to remove more chemicals and impurities.

The important things to consider are how much carbon is in the unit as well as how much time the contaminant spends in contact with it.

They are usually rated by the particle size they can remove, ranging from 50 microns to 0.5 microns, which is the most effective.


How Do Activated Carbon Filters Work?

The carbon in an activated carbon filter, whether it is in granular or block form, has been treated so that it is extremely porous.

A small amount of carbon, four grams, has a surface area that is equivalent to that of a football field. This is what gives them their effectiveness.

Water flows through the filter, and the impurities stick to the carbon. How effective the filter is depends on both the temperature and the flow of the water. Smaller filters should be used with cold water and low pressure.

What Do Activated Carbon Filters Remove From Tap Water?

Activated carbon filters remove hundreds of contaminants and impurities from tap water. There are 32 identified organic compounds, and it removes them all.

It also removed 14 listed pesticides and the 12 most common herbicides. Specifically, it removes the following:

Chlorine (Cl)

Chlorine is often added to tap water to make it safe, but it can smell and taste bad. Activated carbon filters can remove up to 95% or more of free chlorine in tap water.

Chlorine By-Products

Chlorine has some by-products, especially THMs, which are potentially cancer-causing.

Activated carbon filters are more effective than any other filter at removing these by-products. In fact, the EPA says that it removed the 32 most common chlorine by-products.

Chloride (Cl-)

Activated carbon filters remove as much as 50% of chloride from tap water.

It isn’t harmful; as a matter of fact it is a natural mineral that helps regulate blood pressure and the pH of bodily fluids. But it does cause a salty taste.


When pesticides are used to control outdoor pests, they end up in groundwater and oceans, and they sometimes make it into tap water.

Activated carbon actually removes the 14 most common pesticides, such as:

  • Chlordane
  • Chlordecone (CLD / Kedone)
  • Glyphosate (Round-up)
  • Heptachlor
  • Lindane
  • Nitrate


Herbicides, also known as weed killers, also make their way into the groundwater and can end up in tap water.

There are 12 common herbicides, including Atrazine, that are removed by activated carbon filters.


Nitrate is a compound with Nitrogen that is important for plants.

It comes from septic tanks, fertilizers, and manure storage, and it isn’t harmful in small amounts, but it can lead to Methemoglobinemia, or a lack of oxygen.

Activated carbon filters remove 50% to 70% of nitrate.


This is a synthetic chemical, and it is found in stain repellents, metal plating, and fire extinguishers.

It has been found in the environment now, and it is toxic. Activated carbon removes PFOs from tap water.


This is another contaminant that is important to plants. Although it hasn’t been shown to harm people, activated carbon filters do remove 70% to 90% of phosphates.


Lithium is found in many water sources, including geothermal waters, oil-gas field brines, and continental brine water.

It doesn’t have harmful effects on humans, but activated carbon filters remove it.


The discharge of many pharmaceuticals has resulted in their existence in drinking water. The concentrations may be low, but activated carbon filters remove 95% of them.

This is important because pharmaceuticals can be harmful if they make their way into your tap water.


There are many types of microplastics that may or may not have chemical additives, and when they break down into tiny particles, they can make their way into tap water.

An activated carbon filter removes all microplastics larger than two microns. These are harmful substances that need to be removed.

What Substances Are Not Filtered by an Activated Carbon Filter?

Although activated carbon filters do remove a lot of organic compounds and other impurities from tap water, there are substances that they do not remove.

These filters do not remove healthy minerals, including potassium, calcium, sodium, and magnesium.

In addition, they don’t remove dissolved solids such as minerals, salts, or metals and they don’t remove iron.

It is important to note that activated carbon filters do not remove microbiological contaminants such as viruses, bacteria, coliform, and cysts.

These contaminants can cause a lot of problems, and the chlorine is added to tap water to kill them.

Finally, activated carbon filters do not remove inorganic contaminants, including arsenic and asbestos. These filters may remove between 30% and 70% or arsenic, but if arsenic is known to be a problem, it will not be enough to remove it.


How Is Carbon Activated?

Activated carbon is processed so that it has a very large surface area. It can be further treated to increase its absorption ability.

It is derived from a carbonaceous material, such as bamboo, sawdust, wood, coconut shell peach pits, or coal, to name a few. Once it is derived, it is activated in one of two ways.

The first way is thermal activation. In this process, the carbon is heated using hot gases. Then steam is brought in to open its pores. This process usually involves the use of carbon dioxide, nitrogen, or argon.

The second process is chemical activation. In this process, chemicals are added before the carbonization process. The chemical might be a strong base, salt, or an acid, and once exposed to heat, it activates very quickly.

Activated carbon comes in two types when it is used for tap water filtration. The first is GAC, or granular activated carbon particles. They diffuse quickly, and they are very common in tap water treatment.

Powdered Activated Carbon, which is the particles used in carbon block filters is the other type, and they are very effective as well.

Advantages and Disadvantages of Activated Carbon Filters

The advantages include the fact that they effectively remove many organic compounds from tap water, including some cancer-causing chlorine by-products.

In addition, because they have such a large surface area, they are very cost effective. They are porous and highly absorbent as well.

They are fairly inexpensive and easy to maintain, and they do a great job of eliminating odors and tastes from your water.

On the other hand, if you use a GAC carbon filter, you need to replace it regularly so that it remains effective. It will lose effectiveness over time with wear and tear.

In addition, they are not good at removing chemicals that are not attracted to carbon.

If you need to remove microbiological organisms, such as viruses and bacteria, you will need to make sure your water is chlorinated.

Key Takeaways

Tap water contains many organic compounds and impurities, and it is necessary to filter them. An activated carbon filter is a solution to this problem because it is very effective at absorbing many of these impurities.

When you want to improve the taste and odor and remove impurities, activated carbon filters will do the trick.

These filters are low maintenance because you simply replace them when they are used up.

Carbon is an organic substance, and it removes different contaminants, which makes it a very beneficial type of filter to have.

Water plays a vital role in keeping people healthy, and it is important to have clear drinking water that is free of these impurities.

When activated carbon filters are used to filter tap water, it makes the water healthier. It also improves the taste and the odor.

These filters are easy to maintain and inexpensive, and, most importantly, they don’t remove the good minerals from the water.

There are many ecological, economic, and health benefits to using these filters in your home.

Jon Agarwal

Jon Agarwal works as an environmental consultant focused on water resources, and he volunteers his time for non-profit organizations. He lives in the heart of Melbourne with his beautiful wife, two sons, and three Persian cats. He particularly enjoys working part-time as it leaves him the time to work on his own writing and share his knowledge. Visit our About page to learn about the contributors of Healthy Buddys.

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