Abstract: A flow collector/distributor for a water treatment tank comprises a housing proportioned to communicate through a wall of the water treatment tank to provide flow communication between the tank interior and the tank exterior. The collector/distributor defines an inner end to project inwardly from the tank wall and an outward end to face outwardly from the tank wall. A plurality of slots are defined in the tubular housing, positioned to communicate with the tank interior when the collector/distributor is seated in the tank wall. The slots are of a width which is narrow enough to permit water flow therethrough while substantially preventing passage therethrough of water treatment material present within the tank.