Abstract: A fluid treatment system having in one version an irradiation chamber with UV lamps with a swirl vane pack in the inlet for effecting clockwise and counterclockwise swirl in fluid entering the chamber. Other versions employ a central filter media element with an irradiation chamber with UV lamps disposed annularly thereabout. In other versions, mechanical wiper discs are provided for wiping debris from the filter media and the lamp tubes. In other versions, the UV lamps are in a central irradiation chamber with plural filter media tubes arrayed annularly there around. In other versions, mechanical wipers are provided for the UV tubes and a rotating drain arm is provided for backwashing individual filter tubes. In other versions, the central filter and annularly arrayed UV tubes are mounted in a pressure vessel lid.