Fluid filter with transparent casing region

A fuel / water filter / digger for Aufschraubverbindung to a mounting base has a sheath and a valve disposed within the shell filter media. The shell has an open upper end and a substantially closed lower end. The sheath is made of an opaque plastic except for a window in the sheath, consisting of a substantially transparent plastic. The substantially transparent plastic window is insert formvergossen with the opaque plastic. The filter medium is disposed in the casing for filtering fuel. The shell defines a water collecting area laid below the filter medium, wherein the window of the sheath is positioned so that it overlaps at least a portion of the water collecting portion to allow a water level monitoring.