A filtration module includes a stack of at least two spacers. At least one spacer in the stack includes a first and a second outer plate and at least one internal permeate channel arranged in between the first and second outer plates such that the outer plates form two of the walls that define at least one internal permeate channel. The at least one internal permeate channel extends between two opposite side, other than the first and second outer plates, of the spacer. Moreover, the first and second outer plates of at least one spacer are porous or perforated and a filtration membrane is attached to the first and second outer plate of at least one spacer such that liquid transferred across the membrane is further transported through the pores or perforations to the at least one internal permeate channel. The spacers of the stack are separated by separate elongated distance-pieces that are attached to the outer plates along the edge to the opposite sides between which the internal permeate channels extend, thereby forming filtrate channels between adjacent spacers in the stack, and wherein the filtrate channels extend in a direction other than the direction of the permeate channels. A method for producing a filtration module and a filtration device are also disclosed.