A check valve assembly has a coupling sleeve with a first end for connection to a pop-up or fixed sprinkler head and a second end for connection to a water supply, the coupling sleeve incorporating a valve seat. A disc valve is retained below the valve seat, and a separate actuator is movably mounted above the seat for movement between an operative position extending through the valve seat to hold the valve in the open position, and an inoperative, retracted position. The disc valve is retained against the valve seat around its peripheral edge, and has a central portion which is moved by the actuator into the open position when the sprinkler head is properly connected to the coupling sleeve. Release or removal of the actuator as a result of removal of the sprinkler head will allow fluid pressure at the second end of the coupling sleeve to urge the valve into the closed position.