A flow-through fluid purification device (1), which comprises a container (5) arranged such that fluid to be purified can flow-through a volume (8) of the container (5) from an inlet (3) to an outlet (7), a receptacle (10) for accommodating a radiation source in the form of a lamp (13), wherein the receptacle (10) has an interface wall (11) permeable for radiation with a wavelength in the UV-range, preferably between 150 nm and 200 nm, more preferably of 172±8 nm, and arranged to let radiation pass into the volume (8) of the container (5), a plurality of baffle plates (9) located in the volume (8) of the container (5) with an inter-baffle distance (D) in the flow direction from the inlet (3) to the outlet (7), wherein the baffle plates (9) are arranged to force the fluid flowing from the inlet (3) to the outlet (7) to flow substantially along the interface wall (11) and through gaps (G) between the interface wall (11) and the baffle plates (9) defining the shortest distance between the interface wall (11) and the baffle plates (9), and wherein the baffle plates (9) each have a surface on the upstream side in the flow direction which is perpendicular to the interface wall (11).
