Abstract: A high pressure liquid dispenser for the delivering preferable sterile liquid with high pressure to a catheter. The dispenser includes a flexible or weak wall storage container in which the liquid to be dispensed is stored and a conduit from the front end wall of that container for dispensing liquid to a catheter. A pressure container around the storage container is stiff enough to take up the pressure of the liquid and the deformation of the storage container, so that the pressure of the liquid elevated by the pump piston may be substantially greater than without the protective pressure container around the storage container. A fluid actuated drive acts on the pump piston. The piston of the fluid actuated drive and the pump piston are respectively so shaped as to provide a pressure boost for producing higher pressure in the liquid in the storage container to produce the jet.