Abstract: A cartridge-type valve is disclosed which is capable of having the flow of hot and cold water to the valve reversed for use in back to back installations. An adapter gasket is provided which has three independent pathways. In one position, the adapter effects respective fluid communication between hot and cold water inlet pipes and hot and cold water inlets in the stationary valve portion. In a second position, when the adapter gasket is removed from the valve body and turned over, communication between the hot and cold water inlet pipes and the hot and cold water inlets in the stationary valve portion is reversed. In both positions, the adapter gasket also effects communication between the outlet of the valve and the outlet of a valve housing, and further it seals all connections at all times.