Abstract: A portable, manned method and apparatus for cleaning cooling towers having a water collection basin at the base while permitting the tower to continue in operation comprises removing water and particulate contaminants from the bottom of the tower basin by venturi suction or aspiration through a tubular wand having an elongated wide opening to draw in water and particulate matter from a defined area of contact. The suction wand is moved around the bottom of the cooling tower basin to remove water and particulate matter therefrom. The removed water is filtered to separate coarse contaminant particles therefrom. The filtration is by a plurality of screens positioned one above another of successively finer mesh from top to bottom and having a motor for vibrating the screens to remove collected particulate matter therefrom. A collector is positioned adjacent to the ends of the screens to receive the particulate matter discharged by vibration of the screens by the motor.