A device for dewatering bulk or free-flowing input material by compacting it is provided. The device has a housing arranged along an axis of rotation, which has an input area and a feed and compaction area following axially within a jacket pipe. In the housing, a coaxial drive shaft with circumferentially extending coils rotates, compacting the input material during transport from the input area through the feed and compaction area. In this process the residual water present in the input material is conducted through radial openings in the jacket pipe from the device. According to the invention it is provided that at least in a partial region the jacket pipe is provided with passages and inside the jacket pipe an inner pipe is arranged, which lies at least partially with its external circumference against the inner circumference of the outer jacket pipe and which at least in the area of the passages has passage openings that are several fold smaller than the passages in the jacket pipe.