Abstract: The invention provides a liquid filter which is economically fabricated from commercially available flat and tubular plastics stock. The filter is openable from the top of replace filter elements carried by filter pipes that are rigid with the lower casing structure, all without disturbing the inlet and outlet fittings of the filter. At the casing top there is a connector block which has both such fittings and which is permanently attached to the lower casing structure. Removably attached to the connector block is a cap construction which has an outlet manifold passage that communicates, via a separable joint, with the outlet fitting of the connector block. Non-leak separable sealing joints are provided between the filter pipes and the cap construction, at the manifold passage.