Sustainable water management is a global challenge. While the United Nations (UN) Sustainable Development Goal (SDG) 6 specifically addresses clean water and sanitation, water pollution is intertwined across many goals and has implications for food security, health, wellbeing, biodiversity, and ecosystems.1 In Europe, despite increased awareness about the importance of sustainable water management, and legislation such as the European Water Directive Framework, a complete regional picture of water quality does not exist.2 This is echoed at the global level. To address this challenge, the UN recognises the significance of incorporating non-traditional data sources, such as citizen science, into water monitoring practices. This policy brief describes the challenges of sustainable water management and how citizen science and public participation can help. This is just one example of an issue within the environmental regulation and climate resilience agenda that could benefit from citizen science. The brief provides a set of very practical recommendations for national water regulators, for national level environment agencies and for the Directorate General for the Environment of the European Commission about how to support citizen science initiatives to address some of these issues in water management.