UPSTREAM addresses the targets of the Mission by overcoming challenges related to the monitoring, prevention, elimination, and valorisation of litter (L), plastics (P), and microplastics (MP). Demonstrating a suite of 14 solutions addressing pollution at every step in the water system, connected to 7 rivers in 5 countries, will enable the co-creation of an extensive database of knowledge and sustainable business models with a focus on making information as widely accessible as possible. The involvement of wastewater treatment plant (WWTP) owners, industrial partners with existing supply chains, innovative SMEs, and a water cluster association will ensure exploitation of the project solutions, while €500k in cascade funding will enhance replication across Europe. The UPSTREAM consortium will thus establish circular value chains with the potential to decrease plastic litter by 50% and MP pollution by 30%. The advances in UPSTREAM are based on best-in-world innovations, including: • Standardised, rapid monitoring techniques able to detect MP down to sizes >25 μm • Bio-based, biodegradable plastics the stop the formation of MP in consumer products and WWTPs themselves • Elimination of more than 90% MP within WWTPs from both sludge and effluent streams • Innovative floating platforms capable of removing >83% of L, P, and MP directly from rivers at both the surface and riverbed, without creating noise pollution or harming ecosystems • Production of relevant monomers from recovered plastics through both advanced fractionation and depolymerisation and biotransformation UPSTREAM represents a pan-European consortium with 5 demo sites across Europe, including 4 WWTPs (UK, ES, DE, IT), plus a testing area on the Danube in Serbia. The consortium is strengthened by top European RTOs, the world leader in sustainable bioplastics development, Novamont, and completed by partners dedicated to creating a digital knowledge sharing platform and engaging with citizens and stakeholders.