Abstract: A method and apparatus for treating contaminated water without addition of chemical agents. A treatment zone is provided, having water-impermeable bottom and side walls, the bottom sloping stepwise from an input end to an output end. Soil is disposed within the treatment zone, and plants are grown therein. Contaminated water is applied to the input end of the treatment zone and flows through the soil to the output end, thereby being treated by the soil and providing nutrients to the plants. Treated water is collected in a collection area at the bottom of the output end, from where it is removed for use.