Abstract: The fluid filtering unit comprises a filter element through which fluid being filtered must pass and a device for cleaning the filter element in situ without interruption of the filtering process. The cleaning device comprises a collector movable between a first position and a second position relative to the filter element on the upstream side of the filter element during a cleaning operation, a device for urging the collector at least in use towards its first position relative to the filter element, an arrangement for moving the collector from its first position to its second position relative to the filter element against the force of the urging device, and a valve arrangement for automatically connecting the collector to dump at a pressure less than that of the fluid being filtered as the collector moves from its first position relative to the filter element towards its second position relative to the filter element.