NOVELTY - The method comprises introducing micro-organisms at a waste water origin point or in its vicinity. The waste water origin point is the beginning of the process of decomposition and dissolution of the organic components of the waste water. A substantial part of the process takes place in a bioreactor located near the waste water origin point, from which the waste water outflows as dirty water. The process continues throughout the entire common sewer system up to a dirty water treatment plant. The process is carried out at a temperature of 8-45 degrees C and carried out in an anaerobic environment.    USE - The method is useful for treating waste water from sinks, baths, showers, washing machines and dishwashers in a common sewer system for producing treated water for watering and fertilizing crops (all claimed).    ADVANTAGE - The method is capable of economically treating the waste water without generating odor, clogging of sewer system by sludge deposits and using chemical cleaning and washing agents in an environmentally-friendly manner thus providing the treated water with less range of chemical oxygen demand and biochemical oxygen demand.    DETAILED DESCRIPTION - The method comprises introducing micro-organisms at a waste water origin point or in its vicinity. The waste water origin point is the beginning of the process of decomposition and dissolution of the organic components of the waste water. A substantial part of the process takes place in a bioreactor located near the waste water origin point, from which the waste water outflows as dirty water. The process continues throughout the entire common sewer system up to a dirty water treatment plant. The process is carried out at a temperature of 8-45 degrees C and carried out in an anaerobic environment. The waste water outflows from the bioreactor as dirty water directed to a pumping station, from where the waste water is forced through a buffer tank for coagulation and treatment in a lamella separator and in filters with granular beds, and is then sterilized with UV radiation. The black water and grey water as waste water are entered into the common sewer system through separate ducts. The black water is introduced to the bioreactor, in which the process of further treatment takes place and black water is converted to dirty water, which is evacuated from the separator to join grey water. The grey water is collected from the point of origin with a separate sewer, strained through sieves and directed through a buffer system for treatment in biological filters. The black water and grey water are evacuated through separate sewer systems. The grey water is: directed through the buffer system to sieves for straining and for further treatment in biological filters; supplied with a pressure booster to a toilet bowl and urinal flushing system; directed to a heat recovery system for heating to provide domestic hot water before entering to the treatment system; collected in an auxiliary tank, after the treatment in the biological filters; sterilized with UV radiation after the treatment and before entering the toilet bowl and urinal flushing system; and coagulated and treated in the lamella separator and treated in granular filters after the treatment and before entering the toilet bowl and urinal flushing system. The black water, grey water and urine are separated at the point of origin and evacuated through separate sewer systems. The urine is collected in a special tank.