A device for filling or discharging a liquid includes an elongated body, a coaxial closure sleeve mounted axially on the main sleeve, wherein the main sleeve is slidable relative to the closure sleeve and the body and comprises an outlet end on its side remote from the body and an inlet end on the side closer to the body, facing the liquid inlet, at the inlet side the main sleeve has lateral surface outflow openings, a push-button for actuating the liquid outflow located at the outflow end of the device, located on the main sleeve at its outlet end side, which the push-button is non-rotatably mounted thereon, and between the main sleeve and the closure sleeve a sealing diaphragm, as well as the helical spring of the push-button are arranged. The liquid flows by axially displacing the push-button member.