A regulator valve has a housing with a seal member therein. First and second plungers are movable in the housing toward and away from the seal member. The plungers are sealed to the housing and have passages therethrough. The plungers are biased toward the seal member by fluid pressure at the housing outlet end. The plungers are biased away from the seal member by a spring. First and second diaphragms connected to the plungers engage the housing inner wall in sealing engagement so that fluid must flow through the passages. The diaphragms and housing define an expansion chamber. A port in fluid communication with the expansion chamber allows selectable introduction of pilot pressure into the expansion chamber to force the first plunger into engagement with the seal member and prevent flow through the passages. In an embodiment of the regulator valve, the water inlet may be oriented at some divergent angle with respect to a water outlet such as 90 degrees.