Abstract: A device for filtering and purifying tap water in combination with a conventional water cooler and bottle includes a generally circular annular flange having an outer diameter sufficient to prevent insertion of the flange into the water-receiving chamber of a conventional water cooler, and having an inner diameter dimensioned to accept a water bottle for use in the water cooler, and having a rigidity capable of supporting the water bottle. Depending from the flange, a generally cylindrical canister of water-impervious material, having an outer diameter and length is dimensioned to fit within the water-receiving chamber. A lower retaining means, capable of passing water while retaining a filter medium, is positioned within the canister at its lower end. A silver-impregnated activated carbon filter medium, capable of removing chlorine and absorbable organic chemicals from potable water, positioned on the upper surface of the lower retaining element.