Abstract: The invention contemplates a self-contained unit wherein a continuous flow of contaminated liquid, such as steam-plant condensate recycled as feedwater, may be processed on an on-line basis through a replaceable demineralizing resin bed and through a replaceable filter cartridge. The disclosed configuration incorporates two cylindrical chambers within a single housing. Flow for demineralizing purposes is directed downwardly through the resin bed in the space between chambers, and the thus-demineralized flow is then directed upward through the filter cartridge in the inner chamber.