These replaceable Activated Carbon Discs reduce chemicals and heavy metals as well as removing bad taste and odour, each effective for up to 500 litres - Our standard activated carbon discs used in all LifeSaver products have been tested to show excellent and consistent heavy metal and chemical reduction for their stated life over a range of sample contaminants such as chlorine, lead, nickel and cadmium. Improving taste and odour along the way. The activated carbon filter is fitted to the underside of the Jerrycan tap. The microbiologically clean water which has been passed through LifeSaver's ultra filtration cartridge then gets filtered through the carbon disc. This 5 pack of activated carbon filters will filter 2,500 litres of water before a replacement pack is required.