Making waves: Benefits of "Big Science" - mobilising research infrastructures for urban drainage.

Urban drainage (UD) faces major challenges internationally, including climate change, deteriorating infrastructure, and new emerging pollutants. Its innovation capacity is constrained by fragmented national research efforts. Adopting a "Big Science" transnational access (TNA) approach, centred on open, distributed Research Infrastructures (RIs), can accelerate progress by strengthening collaboration, harmonising protocols, and enabling FAIR-aligned, quality-assured data workflows. The Co-UDlabs project demonstrates how transnational access to distributed RIs can mobilise expertise, broaden stakeholder and industry participation, and generate robust evidence for policy and operational practice. Scaling this model across Europe and beyond could reduce duplication, enhance trust in innovation, and support long-term transformation of the UD sector. Big Science principles can help better position UD as a strategic field for societal investment essential for urban resilience and the achievement of UN Sustainable Development Goals.