This document summarises outcomes relating to water quality and waterbody conditions from the report ‘Nature-based Solutions: State of the Art in EU-funded Projects’ (Wild et al. (Eds.) 2020) prepared through the EC’s Valorisation of NBS Projects Initiative. EU research and innovation projects were scanned for results pertaining to key areas such as Water Framework Directive implementation, cross-compliance with the Common Agricultural Policy, catchment management, diffuse pollution and waterbodies. Evidence from the reviewed projects (and the EC’s NBS policy topic area) is framed within knowledge from the literature in the realm of water policy, to give as full a picture as possible about the state of the art with relevant NBS. Contextualised information is provided on policy developments, research results and key lessons. The resulting evidence base includes figures and monetary values showing the relative cost-effectiveness of NBS, and exploring how they support water policy implementation. Policy recommendations and knowledge gaps are also highlighted to support the strengthening of strategies and practical action for the uptake of NBS, to deliver targeted and efficient interventions to help solve societal challenges in Europe and beyond.