A control valve includes a valve body with a plurality of ports and a plurality of annular flow passages. At least one valve element such as a piston which includes a plurality of annular flow passages and a longitudinal flow passage is selectively movable within a bore within the valve body through operation of a valve controller. The valve controller includes a motor that is selectively operative to control the position of the at least one valve element to enable liquid flow through a plurality of flow paths. The valve may be utilized in system arrangements which oxidize and filter out contaminants in liquids such as water.