Method for operating a water treatment plant comprising - at least one container with means for water treatment requiring, in particular, periodic regeneration, - a valve system for controlling volumetric flows in the water treatment plant, comprising a movable control element and a counter-element arranged in a stationary manner in a housing of the valve system, the control element bearing in a sealing manner against the counter-element and being capable of being moved successively, periodically repeatedly into at least two operating positions (P1, P2, P3) of an operating cycle with differently configured valve functions relative to the counter-element , - a sensor for determining the current position of the control element relative to the counter-element , and - a device for reversing the direction of movement of the control element relative to the counter-element , wherein the direction of movement of the control element is reversed at least once per operating cycle, wherein a reference position (R) of the control element is determined by means of the sensor , and wherein the current position of the control element is ascertained from the reference position (R), the movement speed v and the running time T of a motor, characterised in that the reference position (R) is offset from the individual operating positions (P1, P2, P3) in each case by a segment x > 0. - at least one container with means for water treatment requiring, in particular, periodic regeneration, - a valve system for controlling volumetric flows in the water treatment plant, comprising a movable control element and a counter-element arranged in a stationary manner in a housing of the valve system, the control element bearing in a sealing manner against the counter-element and being capable of being moved successively, periodically repeatedly into at least two operating positions (P1, P2, P3) of an operating cycle with differently configured valve functions relative to the counter-element , - a sensor for determining the current position of the control element relative to the counter-element , and - a device for reversing the direction of movement of the control element relative to the counter-element , wherein the direction of movement of the control element is reversed at least once per operating cycle, wherein a reference position (R) of the control element is determined by means of the sensor , and wherein the current position of the control element is ascertained from the reference position (R), the movement speed v and the running time T of a motor, characterised in that the reference position (R) is offset from the individual operating positions (P1, P2, P3) in each case by a segment x > 0. wherein the direction of movement of the control element is reversed at least once per operating cycle, wherein a reference position (R) of the control element is determined by means of the sensor , and wherein the current position of the control element is ascertained from the reference position (R), the movement speed v and the running time T of a motor, characterised in that the reference position (R) is offset from the individual operating positions (P1, P2, P3) in each case by a segment x > 0. <EOS>