Public awareness of the issue of micropollutants in aquatic systems is increasing. It was shown that micropollutants occur also in drinking water resources in relevant concentrations. As Lake Constance serves as a large drinking water reservoir, it is important to investigate the occurrence and fate of micropollutants from their sources into rivers and finally into the lake. In a previous study, which comprehensively investigated micropollutants in the open water of Lake Constance, it was found that most substances in the lake were originated from urban areas. The seven most frequently detected micropollutants were carbamazepine, diclofenac and sulfamethoxazole (pharmaceuticals), benzotriazole and methylbenzotriazole (anti‐corrosives) as well as sucralose and acesulfame (artificial sweeteners). These substances were therefore selected to be investigated in further detail. The main goals of this study were firstly to determine current contamination hotspots of the seven selected micropollutants in the catchment of Lake Constance and to investigate how the current load input into Lake Constance affects its water quality. Secondly, different strategies to reduce these hotspots in the catchment and in the lake were evaluated. The reduction of micropollutants was considered to be achieved by an upgrade of waste water treatment plants (WWTPs) by an advanced treatment step such as ozonation.