A valve for switching over liquid paths, particularly for pressure exchanger installations with tubular pressure exchanger chambers (3) through which an alternating flow occurs, in which a rotatable control element (10, 10.1) having a plurality of flow paths is mounted in a housing (11), which in turn comprises a plurality of connection opening (12, 16, 17, 46) connected to a first pipe system and to an end of at least one pressure exchanger. Another end of the pressure exchanger is connected to a second pipe system through a valve. A motorized drive shaft (50) rotates the control element so as to alternately connect the control element flow paths to openings inside housing (11). Oncoming flow to the control element may come from an axial direction or from a radial direction, and outgoing flow from the control element occurs in the axial direction.