Abstract: A method and apparatus for filtering a fluid through a particulate filter medium and for periodically scrubbing the particulate filter medium of accumulated contaminating material. During the filtration cycle, the particulate filter medium is retained with a filtration vessel by a bottom screen. During the scrubbing cycle, the particulate filter medium is retained within the filtration vessel by the bottom screen and a top screen. The combined surface area of the bottom screen and the top screen is substantially greater than the surface area of the bottom screen alone. During the scrubbing cycle, the particulate filter medium is fluidized with a scrubbing fluid and violently circulated to remove accumulated contaminating material from the filter medium, thereby suspending the contaminating material in the fluidized mixture.