As a water filter media, activated carbon has many applications in the field of water filtration, as it is a highly adsorbent material and a natural way of obtaining filtered water. Fridge filters, shower filters and many domestic water treatment units contain activated carbon in order to remove a wide range of common contaminants found in tap water. Its high capacity to remove chemicals and impurities has been recognised since ancient Egyptian times.

Doulton tap water filter system

Water filter systems usually contain either granular activated carbon (GAC) or powdered block carbon, and multi-stage filtration systems can contain both. Because of their higher ratio of contaminant removal, carbon block filters are deemed to be more efficient. There are three important factors that determine the filtration efficiency of activated carbon filters: quantity, exposure time, and particle size. The more carbon a water filter contains, the better. Likewise, the more time the contaminants are in contact with activated carbon, the better they are adsorbed. The removal rate of AC filters is also influenced by their particle size. The particle size can range from 50 microns to 0.5 microns, which is the most efficient.

With respect to their contaminant removal capacity, AC filters will be efficient in reducing or removing the followings: volatile organic compounds (VOC), herbicides, pesticides, THMs (disinfection by-product), chlorine, benzene, solvents, radon and hundreds of other chemicals. Some AC filters will even remove some heavy metals. AC filters rated 0.5 micron can mechanically remove turbidity, particulates, giardia and cryptosporidium. Carbon filters do not remove viruses and other smaller bacteria.

Because carbon filters are not particularly successful in removing dissolved inorganic contaminants or certain heavy metals, they are sometimes used in combination with other water filtration systems like reverse osmosis or UV water filters. For example, the Puricom Proline Plus 5 Stage Non-Pumped Reverse Osmosis System contains both a GAC filter and a carbon block filter.

To find out whether a standalone AC filter is enough for you, or if you should opt for a multi-level filtration system, you should test your water source to identify the contaminants that they may contain. If your tap water contains substances that are not removed by this filter media alone, then you should opt for a system that combines more water purification technologies.

Doulton water filters usually combine carbon filters with ceramic filters, which is another natural filter media. The Doulton Duo Filter Housing with Ultracarb & Cleansoft Candles is a filter that does exactly that.

Generally, countertop or under-sink water filters contain 350 to 700 grams of activated carbon, which at first may seem as a low quantity; however, considering that 3 g of AC can have a surface area of a football field, 350 grams is actually not a low quantity at all. Bituminous, coconut shell and wood are the most common materials used to create this water filter media, and the most efficient of these three is coconut shell carbon, which is also more expensive.