A system and method to remove pathogenic organisms and other suspended and dissolved containments from sewage or other contaminated water by an inexpensive, nearly maintenance free device. Principles of operation include new effective methods whioch combine synergistically, suspended and fixed film biological reactor, settling chamber, physical filter, and composting technology, to achieve tertiary sewage treatment and equivalent treatment of other contaminated water without outside energy input being required. Contaminated water flows into the apex or center of a large circular, wedge or conic chamber, then radially through precisely shaped layers of medium which provide progressive treatment by reduced pore size and increased surface area as the flow proceeds to the periphery. Oxygen can be diffused into the final treatment stage by providing large surface exposure to ambient air. The treated effluent has a benign health and aesthetic quality to permit disposal as normal surface run-off, used for irrigation and landscaping or allowed to percolate into subsurface soil without clog mat formation.