In a well casing projecting from ground surface to water level and having a wall opening underground between the ground surface and the water level for association with a pump, an adaptor having an elbow port, for communication between an outlet port at the wall opening and a vertically depending inlet tube, is designed for expedient removal from and insertion into operative position. The arrangement includes a pintle on the outlet port affixed to the well casing at the wall opening and a link pivotally connected to the elbow adaptor, which cooperate to locate the elbow adaptor in operative communication with the outlet port when the adaptor is lowered into the well casing and to release the elbow adaptor from such operative communication simply by lifting.