This special issue combines insights from an array of theoretical perspectives, including political ecology, Indigenous studies, and more-than-human and feminist geographies to engage with a critical question for water studies: What are the theoretical, empirical and methodological implications of a closer engagement with the matter and properties of water and infrastructure? To answer this question, the contributions draw on a geographically and empirically diverse set of case studies that illuminate a range of articulations of materiality of water and infrastructures in hydro-social assemblages. Collectively, the papers highlight how the materiality of water is inherently plural, as it is co-constituted through its entanglement with other materialities ( water with), gives rise to emergent materialities through its intra-action with other elements and more than human natures ( more-than-water), and relies on the labour of living organisms to transform and maintain its function ( lively waters). Second, the papers show how apprehending and pluralising materiality of water and infrastructure extends conceptualisations of agency, justice and care in hydro-social assemblages. The third thread emerging from this collection of papers is that methods matter for interdisciplinary, community and more-than-human knowledges. We conclude by identifying potential areas of interdisciplinary practice and future research on the material matters of water/s and infrastructures that engage with the interplay between ecological, hydrological, technical and social processes.