Due to improved chem ical analysis, pharmaceuticals, pesticides and endocrine disrupters are increasingly detected in waters. The waste water treatment plant removes parts of the substances by sorption and biological decomposition. The other part reaches river and lakes together with the treated waste water. This article presents possible measures to eliminate the remaining substances. On the one hand, via sustainable measures on the source, and on the other hand, with technical measures like ozone or activated carbon dosages.