Cross border management of drinking water supply systems is currently a topic that is regularly disputed in bilateral relations between the countries in the Adriatic area. This topic affects not only neighbouring countries but also relationships between regions and communities. The Work Package 5 (WP5) is divided into following activities: • Historical overview of the development of cross border water supply systems (CB WSS); • Development of standard protocols and procedures for efficient and effective cross border water supply; • Long term cross border and regional drinking water supply pricing model.