Abstract: A system and method for selecting one of a plurality of liquid supply receptacles as a source of supply for a liquid dispensing apparatus is disclosed. As liquid is withdrawn from the supply receptacle the dielectric constant of the liquid is sensed in order to detect any undissolved gases (i.e., bubbles) which are present in the liquid. The presence of bubbles within the liquid indicates that a supply receptacle has become empty or indicates a failure of components associated with one of the supply receptacles. Upon the detection of undissolved gases within the liquid withdrawn from a supply receptacle, the present invention causes another liquid supply receptacle to be selected as a source of supply for the liquid dispensing apparatus.