Abstract: This portable container for liquids includes a bottom ring plate on which is nested an upper pressure plate. An elastic membrane overlays the pressure plate to define therewith a chamber for containing a liquid under pressure. The membrane has a circumferential side wall abutting a side wall of the pressure plate, and an inturned wall section engaged between side walls of the ring plate and pressure plate. A nipple having a threaded axial bore opening into the chamber is integral with the pressure plate and extends downwardly through a central hole in the ring plate. A fitting having an externally threaded shank is engaged in the threaded bore of the nipple. The fitting has a radially extending other nipple on which is secured a flexible tube for passing liquid under pressure into and out of the chamber while the membrane expands and contracts. The fitting may have a radially extending head abutting a flange which is integral with the ring plate and surrounds the central hole, to hold the assembly together.