Valve assembly for bags

A valve assembly for use with a liquid container comprises a flexible valve 24 formed with a cap 20 that can snappably close off its top, a housing 22 that secures the valve, and a spout 28 to which the housing is secured. The valve can accept a tube. The tube may be dimensioned to fit within an opening of the housing to create a liquid tight seal. The valve may comprise a raised portion (35, fig. 4B) comprising one or more elements extending from the valve into the opening, to mate with the tube when the tube is inserted into the opening. The valve may comprise one or more valve walls (39) that are configured to collapse in response to insertion of the tube and return to the expanded position upon removal of the tube from the housing. The valve may be configured to form a seal with the housing when the valve walls are in the expanded position, and reveal a space between the tube and the valve to allow fluid to flow between the tube and the valve in the collapsed position. The valve is preferably a duckbill valve.