WaterMan promotes the reuse of water in the Baltic Sea Region. Thus, it adds a new element to water management that can make water supply more climate resilient. The key actors for water reuse are local authorities and water companies, for most of which the topic is still a novelty. WaterMan will supply them with knowledge and tools to develop strategic approaches and to implement concrete measures that bring water reuse into practice. The capacity building process involves a transnational peer learning process. Municipalities and water companies from 6 countries will, assisted by R&D institutions / domain experts, co-create: (1) Exemplary water reuse strategies for selected model regions that combine measures for (a) reuse of treated water (b) recirculation of retained water (c) promoting stakeholder & consumer acceptance for water reuse. (2) A set of complementary pilot measures for water reuse that depict typical use cases, and that adapt, test and validate concrete solutions for utilisation in the BSR. The results are processed into a “BSR Water Reuse Toolbox”. It gives other local authorities & water companies concrete guidance on how to foster water reuse and is pro-actively & widely disseminated to them. Geographically, WaterMan focusses on the southern parts of the BSR (southeast SE, DK, DE, PL, LT, LV, EE). This concentration on a homogenous geology & landscape type will make peer learning and knowledge transfer more effective.