Water enters the valve from the system main line and exerts a force against the center of the valve’s diaphragm. A small orifice in the diaphragm allows the water to flow through to the upper chamber between the diaphragm and the bonnet. The water continues to travel on through a port in the bonnet to the solenoid area. The solenoid has a light spring loaded metal piston that, when the valve is closed, covers the inlet port hole.