Filter cartridge assembly

A filter cartridge assembly assembled from two disposable filter elements and spacer means holding the filter elements in separate spaced apart relationship, each filter element comprising an outer housing containing an annular paper core, characterised in that the spacer means comprises a reusable back-to-back filter element support means with through holes for flow of filtrate flowing through the annular paper core into the spacer means, the spacer means having cross flow passage means within said spacer means for inward flow of said filtrate for return through a return pipe, the spacer means being supported by a reusable outer locator ring in which the spacer means is located and which extends in opposite directions outside a peripheral marginal portion of the housings of the respective disposable filter elements.