Service water backwashing filter

In a service water backwashing filter having a pipe housing with axial through flow, which pipe housing is provided with one flange each for installation between neighbouring pipes of a water supply and a radial discharge for the filter cake through a discharge pipe and having a plurality of filter cylinders which are arranged on a sector of a housing base receiving the feed water inflow, which housing base is held between flanges, a drive being provided for aligning the discharge pipe with the filter cylinder during backwashing with filtrate, according to the invention it is provided that the pipe housing (1) is flanged from one each of two housing pipes (4, 5), the inner housing flanges (6, 7) holding the housing base (10) and the outer housing flanges (38, 39) serving for flanging onto the supply pipes, and that the outer flanges (38, 39) surround orifices (36, 37) in domes (34, 35) which close the outer ends of the pipe housing (1) and decrease the internal cross-section of the filter housing to the internal cross-section of the supply pipes (Fig. 1).