A particulate media filter employing a continuous media backwash, designed to promote mass or plug flow of the filter media within a filtration vessel and to eliminate areas of stationary media particles. The filter vessel contains a filter bed moving downwardly, countercurrent to an upwardly-moving solids-contaminated influent or feed stream. The contaminated liquid is cleaned by its passage through the filter bed, and is removed as filtrate from a location in the vessel above the top of the filter bed. The downwardly-moving filter bed media becomes progressively more contaminated, and is removed from the filtration stream near the bottom of the filter vessel for cleaning and recycling into the filter stream. A frustoconical skirt-like perimeter feed profile is disposed on the interior of the vessel, surrounding a conical center feed profile, under which may be placed a coaxial center feed pipe. A single, large, substantially unobstructed annular channel for countercurrent flow of influent and filter media is defined between the two profiles. The influent is introduced into the filter vessel between the perimeter feed profile and the wall of the vessel, and under the center feed profile via separate feed distribution channels fed by a common feed header, subsequently entering the filtration stream from underneath the profiles.