The Green Agenda for the Western Balkans, through its pillars, addresses the initiatives to support the region in developing circular economy (CE) strategies and fighting pollution of air, water and soil. Driven by increased demands in water, energy and food, and simultaneously with the necessity to reduce environmental impact, the water treatment sector urges for innovative solutions. According to this wastewater can potentially contribute to the nexus of water, energy and material recovery, concerning the circular-economy design. The SmartWaterTwin project aims to boost knowledge and research excellence in the area of sustainable wastewater treatment and management by increasing the scientific and technical capacities of widening institutions. In the long run, SmartWaterTwin will initiate the paradigm-shifting from linear (traditional) toward a circular (future) model in the water sector in The Republic of Serbia. In addition, it will serve as a “soft instrument” for assessing the boundary conditions for circularity by influencing knowledge levels, collaboration and policy creation. Analysis assessment for the potential benefits of the circular economy for Serbia will be performed and can be extrapolated for WB region. Indicators measuring performance towards the development of CE are competitiveness and innovation, which will be unleashed throughout the project objectives. The project will provide an opportunity for twinning in a coherent international approach to the circular economy through developing a comparative analysis from two perspectives - "thinking and rethinking" of circular economy in the water sector. The project will change the perception of wastewater- do not think about waste but about the source.