Abstract: With the method for the purification of sewage waters, in a first purification stage favorable conditions (pH, suspended matter) for the growth of ubiquiteous nitric bacteria are adjusted, whereby the loads of ammonia are to the major extent converted to nitrate. In a subsequent second purification stage in the form of a fixed mineral bed planted with emersed helophytes, the nitrate is reduced to nitrogen, and phosphate, sulfur, heavy metals and refractory carbon compounds are eliminated.