Raw materials for activated carbon production like wood, coal, and coconut shells

The Role of Activated Carbon in Water Filters

Understanding Activated Carbon

Definition of Activated Carbon

Activated carbon, also known as activated charcoal, is a specialized form of carbon that has undergone processing to create a vast network of tiny, low-volume pores. These pores dramatically increase the surface area available for adsorption or chemical reactions. To put it in perspective, a single gram of activated carbon can have a surface area of over 3,000 m², equivalent to the area of over half a football field.

The Production Process of Activated Carbon

The production of activated carbon involves two main stages. The first stage is carbonization, where carbon-rich materials such as wood, coal, or coconut shells are heated at high temperatures in an oxygen-free environment. This process reduces the volatile content of the material and leaves behind a carbon-rich char.

The second stage is activation. The char is activated by exposing it to an oxidizing agent, usually steam or carbon dioxide, at high temperatures. This process erodes the internal structure of the char, creating a vast network of interconnected pores. The result is activated carbon, a material with an incredibly high surface area and excellent adsorptive properties.

The Unique Properties of Activated Carbon

Activated carbon's unique properties make it highly effective at trapping various substances. Its vast network of pores provides a large surface area for adsorption, allowing it to capture a wide range of chemicals and pollutants. Furthermore, the size and distribution of the pores can be tailored during the activation process to target specific types of contaminants, enhancing the material's overall effectiveness.

Activated carbon filter installed in a home water system

The Function of Activated Carbon in Water Filtration

The Science Behind Activated Carbon Filtration

Activated carbon filters water through a process known as adsorption. This is not to be confused with absorption, where one substance is dissolved or merged into another. In adsorption, contaminants in the water are attracted to the surface of the carbon particles and get trapped in the pores.

The effectiveness of activated carbon in removing contaminants depends on several factors, including the physical properties of the carbon, the nature and concentration of the contaminants, and the contact time between the water and the carbon.

Different Forms of Activated Carbon in Water Filters

There are two primary forms of activated carbon used in water filters: granular activated carbon (GAC) and powdered block carbon. GAC is loose, granular carbon that filters water through contact. It's commonly used in point-of-use devices like faucet-mounted filters and pitcher filters.

On the other hand, powdered block carbon has a higher contaminant removal ratio due to its larger surface area. It's typically used in more advanced filtration systems, including under-sink filters and whole-house filters.

Whole-house water filtration system with activated carbon filter

The Advantages of Using Activated Carbon in Water Filters

Broad Spectrum Contaminant Removal

One of the main advantages of using activated carbon in water filters is its ability to remove a broad spectrum of contaminants. These include chlorine, a disinfectant widely used in municipal water treatment that can affect the taste and smell of water, as well as various organic compounds and certain pesticides.

Activated carbon is also effective at removing other harmful substances, including some heavy metals, certain types of radionuclides, and byproducts of the disinfection process. Its effectiveness against these contaminants makes it a valuable component in many water filtration systems.

Enhancement of Water Taste and Smell

In addition to removing harmful contaminants, activated carbon filters can also enhance the taste and smell of water. They can adsorb substances that cause unpleasant tastes or odors, such as chlorine and certain organic compounds. This makes activated carbon filters popular in applications where improving the aesthetic qualities of water is important, such as in home drinking water systems.

scientist checking water after activated carbon filter

The Shortcomings of Activated Carbon Filters

Limitations in Contaminant Removal

While activated carbon filters are highly effective at removing a wide range of contaminants, they do have limitations. For instance, they are not effective at removing minerals, salts, and dissolved inorganic substances. They also cannot remove microbes, such as bacteria and viruses, which can pose a risk to health.

The Need for Regular Maintenance

Activated carbon filters also require regular maintenance to remain effective. Over time, the pores in the carbon can become filled with adsorbed contaminants, reducing the filter's effectiveness. This is known as breakthrough, and it can result in contaminants being released back into the water.

Steps to replace your activated carbon filter

The Importance of Filter Replacement

Determining When to Replace Your Filter

The lifespan of an activated carbon filter depends on several factors, including the quality of the incoming water, the volume of water filtered, and the specific design of the filter. However, a general rule of thumb is to replace the filter every 6-12 months. Some signs that your filter may need replacing include a decrease in water flow, changes in the taste or smell of the water, or a change in the color of the filtered water.

Steps to Replace Your Activated Carbon Filter

Replacing your activated carbon filter is typically a straightforward process. Most water filter systems are designed for easy filter replacement. However, the specific steps can vary depending on the design of your system. Always refer to the manufacturer's instructions for specific guidance.


Activated carbon plays a pivotal role in water filtration, offering broad-spectrum contaminant removal and enhancing the aesthetic qualities of water. However, it's important to understand its limitations and the need for regular maintenance and replacement. By doing so, you can ensure the continued effectiveness of your water filtration system and the quality of your water.


What is activated carbon made from?

Activated carbon is typically made from carbon-rich materials like wood, coal, or coconut shells.

How does activated carbon filter water?

Activated carbon filters water through adsorption, where contaminants are attracted to the surface of the carbon particles and get trapped.

What contaminants can activated carbon remove from water?

Activated carbon can remove a wide range of contaminants, including chlorine, certain organic compounds, some heavy metals, certain types of radionuclides, and byproducts of the disinfection process.

What can't activated carbon filters remove?

Activated carbon filters cannot remove minerals, salts, dissolved inorganic substances, or microbes such as bacteria and viruses.

How often should I replace my activated carbon filter?

A general rule of thumb is to replace your activated carbon filter every 6-12 months, but this can vary depending on the quality of your water and the volume of water you use.

Image Attributes: Image by Racool_studio and Image by macrovector on Freepik

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