Abstract: The present invention relates to a filter provided with a filter bed consisting of a granular material, which does not comprise layers of coarser material. In the filter bed at least one liquid distributor is arranged which defines an expansion space otherwise defined by areas of repose for the bed material, in which space at least one outflow opens above the areas of repose. The distributor is so designed, that the liquid can flow out of the openings with great energy and fill the cavity and fluidize the whole bed, which enables homogenous rinsing of the bed. The opening of the distributor is larger than the mean grain size of the filter bed material and allows fiber, pieces of plastic and similar impurities to pass through the distributor and be removed from the filter.