A pressure regulator for use in a sprinkler assembly including a riser and a sprinkler basket includes an outer sleeve mounted in the riser at an inlet thereof and a pressure responsive member, movably mounted in the outer sleeve and movable from an open position allowing flow of water between the top surface of the filter basket and the bottom edge of the pressure responsive member and up the riser and a closed position where the bottom edge of the pressure responsive member contacts the top surface of the filter basket to prevent water from flowing. The pressure responsive member is biased in the open position and moves into the closed position when downstream water pressure exceeds a predetermined value.