Control device and method for controlling the impingement of the workpiece by a water jet or an abrasive water jet in a cutting unit. Control device includes a feeder composed of at least two flow-through areas positionable between a high-pressure water supply and a jet nozzle of the cutting unit. At least one of the flow-through areas includes a high pressure area, and at least one of the flow-through areas includes a pressure-reducing area. At least one switchable valve is arranged in the high-pressure area, a pressure-reducing mechanism is arranged in the pressure reducing area, and an impingement line is coupled to the at least two flow-through areas and coupleable to the jet nozzle.