Transitions through a lens of urban water

•We demonstrate the value of urban water as a sectoral context for understanding sustainability transitions.•Eight articles by scholars of both urban water and transitions are showcased.•We argue the value of deep case studies using primary data and sector-specific knowledge.•We call for a shared agenda for urban water and transitions research to the advancement of both fields.

This special issue explores transitions in urban water; a sectoral context that provides a comprehensive and representative setting for exploring the dynamics of sustainability transitions. Not only are the ecological, social and technical facets inextricably meshed in urban water systems, in various cities sustainability innovations are gaining legitimacy and taking off against a backdrop of a sector characterised by strong technological and institutional path dependencies. This has the concerted attention of urban water scholarship but not yet transitions studies; this special issue therefore suggests taking steps towards a global, coherent focus for studying urban water sustainability transitions and provides thought-provoking inputs from eight internationally diverse articles, authored by researchers from both urban water and transitions research communities and bring a range of transition perspectives. This editorial reflects upon these contributions, individually and as a whole, to draw synthesised insights, challenges and new ways forward for the study of sustainability transitions.