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 .