Check valve and filter assembly incorporating such valve, especially for water cooler assemblies

A normally open check valve, incorporating a bell-shaped check valve member, and filter assembly incorporating same, wherein the specific gravity of the bell shaped member volume as defined by the throat, and exterior wall of the bell shaped member is less than one, and the bell shaped member is disposed adjacent a valve seat in a chamber with the throat opening thereof generally facing a liquid source, among other things. The low specific gravity for the bell shaped member volume may be attained by way of example, by the bell shaped member interior capturing and retaining a gas bubble when the throat of the member is exposed to a liquid-gas interface, or by a thin member covering the throat of the bell shaped member to encapsulate a gas bubble, or by a foamed synthetic resin material in the interior of the bell shaped member, or a combination thereof.