A hydrant shear valve for a hydrant (12, 112) coupled in fluid communication with a hydrant water supply pipe (22, 116) having a pipe flange (14, 118), the hydrant shear valve (10, 110) comprising: a valve body (13, 121) having fastener receiving openings (11, 150, 160) for mounting the valve (10, 110) in fluid communication between the hydrant (12, 112) and the water supply pipe (22, 116); the valve body (13, 121) having a valve seat; a two-piece valve member (18, 126) pivotally mounted in the valve body (13, 121) to move between an open position and a closed position; at least one bias member (21, 132, 138) for maintaining releaseably the valve member portions (45, 47, 127, 129) in the open position and for permitting the valve member portions (45, 47, 127, 129) to be moved to the closed position under the force of fluid flowing from the supply pipe (22, 116) if the bias member (21, 132, 138) is free; and at least one frangible actuator (25, 148) for breaking away when the hydrant (12, 112) is hit with sufficient impact to free the bias member (21, 132, 138) for causing the valve member portions (45, 47, 127, 129) to move toward the closed position, characterized in that the hydrant shear valve (10, 110) further includes a spring (23, 146) for resiliently urging the valve member portions (45, 47, 127, 129) away from one another when the valve member portions (45, 47, 127, 129) move toward the closed position and the valve member (18, 126) having a pair of valve member portions (45, 47, 127, 129) for being disposed overlapping one another axially aligned within the valve body in the open position and for being disposed in a co-planar configuration in engagement with the valve seat in the closed position. a valve body (13, 121) having fastener receiving openings (11, 150, 160) for mounting the valve (10, 110) in fluid communication between the hydrant (12, 112) and the water supply pipe (22, 116); the valve body (13, 121) having a valve seat; a two-piece valve member (18, 126) pivotally mounted in the valve body (13, 121) to move between an open position and a closed position; at least one bias member (21, 132, 138) for maintaining releaseably the valve member portions (45, 47, 127, 129) in the open position and for permitting the valve member portions (45, 47, 127, 129) to be moved to the closed position under the force of fluid flowing from the supply pipe (22, 116) if the bias member (21, 132, 138) is free; and at least one frangible actuator (25, 148) for breaking away when the hydrant (12, 112) is hit with sufficient impact to free the bias member (21, 132, 138) for causing the valve member portions (45, 47, 127, 129) to move toward the closed position, characterized in that the hydrant shear valve (10, 110) further includes a spring (23, 146) for resiliently urging the valve member portions (45, 47, 127, 129) away from one another when the valve member portions (45, 47, 127, 129) move toward the closed position and the valve member (18, 126) having a pair of valve member portions (45, 47, 127, 129) for being disposed overlapping one another axially aligned within the valve body in the open position and for being disposed in a co-planar configuration in engagement with the valve seat in the closed position.