Abstract: A plumbing adapter for installation in series with a flexible conduit leading to a plumbing fixture, such as a toilet tank or a kitchen or bathroom sink. The adapter has a first end suitable for engagement in sealing relationship with the terminal end of the conduit and an opposite, second end configured to engage the coupling portion of the plumbing fixture in sealing relationship. A threaded side extension having an opening communicating with the water passage within the adapter is provided for coupling to an auxiliary appliance through which water is to be supplied.