The majority of water filters sold use activated carbon in one form or another. Activated carbon is made by carbonising various natural materials like coal or coconut shell and then steam treating it to activate its high surface area.
It is made in granular, powder or porous block form and then made into a cartridge for inclusion within a water filter. When water passes through the carbon, organic contaminants are adsorbed onto the high surface area. It will also reduce chlorine – and, as organics and chlorine are the main causes of complaint about the taste, odour and colour of the water supply, activated carbon filters are very popular for treatment of water for drinking purposes.
Your new drinking water tap uses an activated carbon filter.