What does activated carbon filters remove from tap water?

How do activated carbon filters work?

Activated carbon filters, often referred to as charcoal filters, contain numerous small, porous carbon particles. In fact, just 4 grams of activated carbon can exhibit a surface area equivalent to that of a football field (6,400 m²). This vast surface area enables the filter to effectively adsorb impurities from water.

As water passes through an activated carbon filter, chemical contaminants adhere to the carbon material, resulting in cleaner and purer water. The performance of the filter is influenced by water flow rate and temperature, which is why most compact activated carbon filters perform optimally under low water pressure and with cold water.

Beyond surface area, the contaminant-removal capability of activated carbon filters also depends on the type and quality of the carbon source. Coconut shell-based carbon is recognized for its superior efficiency, though activated carbon can also be produced from wood or coal and is commonly available as granular activated carbon (GAC) or solid carbon blocks.

What does active carbon filters remove and reduce?

Activated carbon water filters effectively eliminate contaminants while also improving the taste and odor of tap water, making them a valuable addition to any household for enjoying the benefits of filtered drinking water.

These filters work by adsorbing both pollutants and added chemicals onto the carbon medium, resulting in significantly purer water. They target a wide range of natural impurities-including bacteria, fungi, and viruses-as well as chemical substances. Key chemical contaminants that activated carbon filters can remove include:

Chlorine: Over 90% of this additive can be eliminated.
Chlorination by-products: Such as chlorides, along with numerous pesticides, herbicides, lithium, phosphates, nitrates, microplastics, and many others.

What Activated Carbon doesn't filter

Although activated carbon filters can reduce over 80 types of contaminants, they are not effective at removing all substances. For example, they do not filter out beneficial minerals like magnesium, potassium, sodium, and calcium-meaning they typically do not lower TDS (Total Dissolved Solids). They also have limited ability to eliminate certain dissolved solids (such as non-contaminant minerals, salts, or metals like iron), many microbiological contaminants (including coliform, viruses, and small bacteria), and inorganic pollutants like arsenic and asbestos, which are only partially reduced. While radionuclides may see some reduction, activated carbon filters are generally ineffective in significantly removing these.

Microbiological contamination is a major concern in regions with inadequate water infrastructure, particularly in relation to waterborne gastrointestinal diseases. Although viruses and bacteria can thrive in natural water sources, public water systems in Europe and North America typically use chlorine to disinfect water, making additional microbiological filtration unnecessary. It's important to note that activated carbon filters alone cannot reliably remove viruses-including coronaviruses that cause COVID-19. However, it should be emphasized that coronaviruses have not been detected in properly disinfected tap water.

In areas where groundwater contamination is an issue, activated carbon can remove only 30–70% of arsenic, which is often insufficient if arsenic levels are high. If your water supply contains any of these substances, it's essential to use a filtration system that combines activated carbon with other technologies-such as ion exchange-to ensure harmful contaminants are reduced to safe levels.

Activated carbon is a highly effective material and technology for water filtration, capable of addressing many-though not all-water quality concerns. It's important to recognize its limitations and select a filter that aligns with your specific requirements.