The invention relates to a water-jet device. The aim of the invention is toimprove the adaptation of one such water-jet device to different applications.To this end, the piston cylinder unit (2) is connected to the eccentric drivedevice (20) in a separable manner and is embodied as an application-specificset with the suction line (4), the pressure line (7), and the operatinghandpiece (3). According to the invention, the piston cylinder unit (2) isespecially provided with an annular fixing region (25) in which the sealingelement of the piston (17) plunges and loses tension in the drawn-out endposition of the piston (17), and the membrane (26) has sufficient free spaceto move.
