a tap for liquids dispenses liquids including wines from plastic bags or bladders packaged in cardboard boxes , and has three modes of operation . liquids may be dispensed from the box on a shelf by manually turning a rotatable cap to open a valve for liquid to flow by gravity ; an adapter attached to the tap automates the process and dispenses liquids through a pump ; and the tap may be used to fill bags or bladders from an automated filling machine . in a first embodiment , the rotatable cap must be manually opened for both manual and automated operation . in a second embodiment , the rotatable cap may remain closed and the adapter can still dispense liquids through the tap using a pump .