A water treatment assembly that comprises a stack of treatment vessels similar to those found in a Bakki shower system. The water treatment assembly is characterised by a filling device 1a on top of and supported by the uppermost treatment vessel in the stack. The filling device comprises a container 2 and a deflection plate 3. The container comprises a base 4 having a plurality of perforations extending uniformly across the whole of the base and a side 5, 6 having an overflow orifice 10, 11. The deflection plate extends along the exterior of the side of the container and defines a channel around the exterior of the container between the overflow orifice and the interior of the uppermost treatment vessel in the stack. At least two sides of the container may be provided with an overflow orifice and a deflection plate.
