A static mixing apparatus for mixing a fluid, preferably a liquid is provided. The mixer comprises a plurality of chambers (5, 8, 12, 15) in series, the first chamber (5) of the series comprising a fluid inlet (4), and the final chamber (15) of the series comprising a fluid outlet (16), each chamber other than the final chamber in the series being in fluid connection with a subsequent chamber, the fluid connection comprising a plurality of orifices (7, 10, 11, 14) dispersed along a direction of flow, the nearest point to the fluid inlet of each subsequent orifice to the inlet overlapping with the furthest point from the fluid inlet of the previous orifice, and being off-set along the direction of flow from the previous orifice.