Abstract: Some embodiments of the invention provide an asymmetric activated carbon block comprising at least a first element and a second element. In some embodiments, the first element can comprise at least two constituents and the second element can comprise at least two constituents. In some embodiments, at least a portion of the first element can be positioned within the second element and at least one of the at least two constituents of the first element can differ from at least one of the at least two constituents of the second element. In some embodiments, the first element and the second element can be asymmetric with respect to a structural property. Some embodiments include part of the first element being located immediately adjacent the second element.

Abstract: A piston for a control valve of a water treatment apparatus includes a body having a central portion from which at least one flange projects radially outward. Each flange has an outer peripheral surface extending around the central portion with an annular groove therein. The annular groove is undercut thereby having a width that increases from the peripheral surface radially inward into the flange. A separate sealing ring is molded into the groove of each flange and is captivated therein by the undercut of the groove. That captivation better enables each sealing ring to resist forces produced by the water flowing through the control valve without becoming dislodged from the flange.