Abstract: A filter press comprises a series of plates and frames separated by filtering sheets into which a liquid to be filtered can be fed via at least two inlet pipes. An outlet pipe is provided to enable filtrate to egress from the press leaving the filtered residue behind in the frames. In order to clean the press, valve means are provided to close off the outlet pipe and to isolate the inlet pipes from each other. A cleaning liquid can then be fed into one of the inlet pipes to pass into the frames and flush out the filtered out residue therefrom via the other inlet pipe.