Low cost sealing drainboard supports adapted for use between adjacent drift eliminator sections in water cooling towers are provided which can be readily installed in the field without the necessity of custom fabrication of structural components, and which give improved drainage characteristics in the form of relatively large, concentrated streams of eliminated water resistant to reentrainment. The preferred supports are unitary, preformed synthetic resin bodies presenting an elongated, eliminator section-receiving channel together with a depending inner sealing wall and a oblique, downwardly and outwardly extending drainage tray. The tray is preformed to present a series of generally V-shaped in plane, increasing depth drainage passageways serving to collect and concentrate eliminated water into relatively large streams resistant to reentrainment in the air currents passing through the tower.