This paper deals with the estimation of the environmental exposition of rubber chemicals to the hydrosphere. After the entry-relevant life cycle steps and representative point source for the "reasonable worst case" have been identified, the emission rate Elocal(water) is determined. The sources of wastewater pollution in the rubber industry are described. This contribution describes the technological data and default values required for the determination of the emission rate. The technique for the determination of the PEClocal(water) with the aid of the complete scenario (emission, sewage treatment plant, effluent in surface water) is demonstrated in an example.