Filter vessel provided with a rinsing trough

In a filter vessel, which serves to contain granular filter material, and comprises a sieve or nozzle bottom for carrying the filter material, at least one open-topped trough being positioned on said bottom, said trough having two top edges and an outlet adapted to be closed, a pipe for feeding a rinsing liquid into the trough to wash out the filter material, said pipe being connected to means for feeding the rinsing liquid into the pipe, the pipe extending over the trough, the pipe being fastened to the edges of the trough by supporting means, the pipe being provided with nozzles, said nozzles having a spraying direction directed into the trough, said nozzles being forwardly inclined toward the outlet of the trough, said pipe having a longitudinal axis extending above said top edges, the angle between said axis and said spraying direction being 10.degree. to 50.degree., the vertical distance A measured between the top edges and said axis being 0.2 to 2 times the outside diameter D of the pipe, and the distance B between the two top edges of the trough being 2 to 8 times the outside diameter D of the pipe.