Abstract: Effluent from a sewage treatment system, such as a septic tank, a settling chamber, or a settling pond is distributed in or over a leaching bed and is percolated in the presence of entrained air through a filter bed that includes a layer of soil with chemical additives having phosphate removal ability adhering thereto in wash-out resisting relation for the purposes of treating the effluent to remove phosphate therefrom and promote the breakdown of bacteria therein.