Abstract: A filter for filtering of a fluid, including a housing having an inlet port for the fluid to be filtered, an outlet port for filtered fluid and an outlet port for filtered fluid and an outlet port for rehect, In a body arranged in the housing to be rotatable between at least two positions of rotation, there are at least two positions of rotation, there are at least two interconnecting flow channels of which at least a first is provided with a filtering means through which filtering takes place in a first rotational position, wherein one end of the first flow channels communicates with the inlet port, and through which backwash takes place in the second rotational position, wherein said end of the first flow channel communicates with the outlet port for reject. The first flow channel is provided with a filtering means at each end. A second of the at least two flow channels connects to the first flow channel between the filtering means and is in constant connection with the outlet port for filtered fluid.