apparatus for backwashing the filter media of a liquid filtering machine while at the same time enabling the machine to filter liquid . the machine is of the type having a tank and a continuous bed of granular filter media in the tank through which liquid having suspended solids therein for removing the solids . the apparatus comprises a partitioning chamber and a carriage for selectively supporting and conveying the chamber above the media bed , with the chamber being insertable into the bed to isolate a portion thereof from the remainder of the bed . the apparatus further comprises a mechanism to selectively allow insertion of the chamber into the bed and to remove it , and a pump to draw liquid through the isolated portion of the bed to backwash it , while filtration may proceed in the remainder of the bed . apparatus for removing the media from the chamber and replacing it with new , cleaned or regenerated media is also disclosed .