A filter apparatus and method for filtering a liquid. The filter apparatus comprises a housing that has at least one inlet for admission of the liquid to be filtered and at least one outlet for discharge of the filtered liquid. The apparatus further comprises at least two substantially cylindrical filter elements that can be fitted into the housing and which have a plurality of openings through which the liquid can flow to filter particles out of the liquid, and at least one filter cleaning element that can be introduced into a respective filter element in a region of an inner surface of the filter element to increase a flow speed of the liquid to be filtered so that substances in the filter element are flushed away. The filter elements are further connected in a parallel arrangement in the filter apparatus.