The invention relates to a water-jet device. The aim of the invention is to improve the adaptation of one such water-jet device to different applications. To this end, the piston cylinder unit (2) is connected to the eccentric drive device (20) in a separable manner and is embodied as an application-specific set with the suction line (4), the pressure line (7), and the operating handpiece (3). According to the invention, the piston cylinder unit (2) is especially provided with an annular fixing region (25) in which the sealing element of the piston (17) plunges and loses tension in the drawn-out end position of the piston (17), and the membrane (26) has sufficient free space to move.
