Climate change (CC) affects fresh water resources and may have significant influence on public drinking water supply. Land use activities exert pressure on water resources and will change according to CC. It is crucial for safeguarding future water supply to anticipate these climate and land use changes and to assess their impacts on water resources. Transnational action is needed to prepare SEE for the challenge of ensuring water supply for society for several decades. Policy makers and water suppliers are required to develop sustainable management practices for water resources, considering existing and future CC influences. Therefore CC-WaterS will identify and evaluate resulting impacts on availability and safety of public drinking water supply for several future decades. Elaborated measures to adapt to those changes build the ground for a Water Supply Management System regarding optimization of water extraction, land use restrictions, and socio-economic consequences under climate change scenarios for water suppliers in SEE. The joint actions to produce this technical system will be performed on a transnational level in the Alps, Danube Middle and Lower Plains and coastal areas representing different SEE-characteristic climates and topography. In CC-WaterS, SEE governmental bodies, water suppliers and research institutions work together and implement jointly developed solutions, hence to be applied on a regional or local level in SEE. The complementary knowledge of the partners, enhanced by further applicable results of past projects, will provide a strong background. Capitalising already existing knowledge and data from EU-funded scientific projects and eliminating parallel investigations, CC WaterS will make information applicable for concrete solutions, develop tools and instruments for public water supply and implement safeguarding measures. An accessory dissemination strategy will ensure that CC-WaterS durable results are transferred to the relevant users.