a composite adsorbent element comprising a packed mixture of granules and fibers , which are desirably granular activated carbon and activated carbon fiber . the element is employed as a filter for purifying tap water . in the composite adsorbent element the activated carbon fibers fill the spaces between the activated carbon granules . the size and relative amounts of the gac and acf are designed to enable water treatment to remove impurities from water more rapidly than conventional filters using granular activated carbon . furthermore , when there are significant time intervals between filtration , a packed mixture of granular activated carbon and activated carbon fibers made in accordance with the invention shows an improved ability to rejuvenate its adsorption capabilities in the time intervals between filtrations .