Activated carbon or charcoal is a natural filter media and activated carbon based filters are used in the majority of water filter systems, mostly as a complementary filter or a standalone filter. Thanks to the highly adsorbent nature and porous surface area of activated carbon, these filters have a good contaminant removal capacity, are good at improving the taste of water, which is why they have a long-standing history as a filter media.
As with any filter media, activated carbon also has some shortcomings, which is why it’s either used together with other filter media (e.g. ceramic filters), or different forms of AC are used to obtain the right concentration that is able to effectively deal with contaminants (e.g. carbon block filters as opposed to granular carbon filters).
What are the pros and cons of activated carbon filters? Here is a breakdown of why these type of filters are very good at their job, and what are some areas in which AC filters don’t excel.
- Natural filter media: this water filter media is created from materials such as bituminous, wood and coconut shell, no chemicals or other substances are added to water, therefore a natural filtration process is achieved;
- Low-cost & easy maintenance: AC filters are one of the least expensive filters and don’t require much in terms of maintenance. Each brand and model of AC filter cartridge has a certain service life at the end of which the filter cartridge has to be replaced;
- Excellent for enhancing the taste and odour of tap water;
- Good at filtering out other carbon-based, organic chemicals and chemical disinfectants like chlorine as well as some microorganisms.
- AC filters are not good at removing chemicals that are not attracted to carbon (e.g. sodium, nitrates, heavy metals, fluoride, etc.);
- Short service life: when the bonding sites in these filters (the ones responsible for “trapping” contaminants) get filled with contaminants, AC filters stop working and need to be replaced;
- The effectiveness of filtration is determined by factors such as the amount of AC and the time water stays in contact with the filter media. Its effectiveness decreases if water does not stay in contact long enough with the carbon filter media;
- AC filters are not effective against some pathogenic bacteria and viruses, and can harbour bacteria, which can lead to bacterial grow-through, however, some filters have managed to avoid this issue by adding trace amounts of silver to inhibit bacterial growth (these filters are known as silver impregnated activated carbon filters).
The disadvantages listed above are the reason why activated charcoal filters are not predominantly used as a primary filter media. Activated charcoal is usually used as a complementary filter media to filter out those contaminants that other filters may not be able to. As mentioned before, no filter media is able to remove all contaminants, and as a result complex filter systems will use several types of filter media to achieve high-quality filtered water.