There is described a fluid treatment system in which fluid to be treated is impinged under pressure on a radiation emitting surface. The fluid treatment system includes at least one radiation source having a radiation emitting surface and at least one nozzle element having a fluid discharge opening spaced from the radiation emitting surface. The fluid discharge opening is configured to impinge fluid to be treated on to at least a portion of the radiation emitting surface. The fluid treatment system is well suited to treating low transmittance fluid.