The panelists and session discussions will contribute to the anthropology of water in two ways. First, panelists will present case studies based on recent ethnographic and historical research exploring the organization of contemporary water worlds. The papers in this session reveal that regimes of water management are more complex and dispersed than they may appear at first, and document how their effects sometimes escape their prognostic claims. The papers explore the creation of a water trust-fund amidst the real estate boom in Costa Rica; how water scarcity is variously understood, experienced, and negotiated in Egypt’s agricultural sector; the reorganization of lands and waters surrounding the Panama Canal as a managed watershed; and the many social pathways through which water traverses urban environments in Egypt. Our second contribution is conceptual. Water worlds are fluid and resist spatial and temporal boundaries, linking contemporary environmental problems and management solutions with other times and places. Drawing on recent work in anthropology, science and technology studies, and geography, panelists will consider how the cultural, economic, technical and political nature(s) of water itself are constituted. The papers seek to contribute to an understanding of the emergent ontologies that water produces and those through which it is produced.