Water is at the core of the most difficult sustainability challenges facing humans inthe modern era, involving feedbacks across multiple scales, sectors, and agents. We suggest that atransformative new discipline is necessary to address many and varied water-related challenges in theAnthropocene. Specifically, we propose socio-hydrology as a use-inspired scientific discipline to focuson understanding, interpretation, and scenario development of the flows and stocks in the human-modified water cycle across time and space scales. A key aspect of socio-hydrology is explicit inclusion oftwo-way feedbacks between human and water systems, which differentiates socio-hydrology from otherinter-disciplinary disciplines dealing with water. We illustrate the potential of socio-hydrology throughthree examples of water sustainability problems, defined as paradoxes, which can only be fully resolvedwithin a new socio-hydrologic framework that encompasses such two-way coupling between human andwater systems.