The water grammar integrates the multiple societal and ecosystem dimensions of water metabolism into a coherent accounting method. It combines the distinct narratives for the analysis of ecosystem and societal metabolic pattern, including the different definitions of hierarchical levels of organization, functional compartments, and semantic accounting categories. Within the societal view, definitions are based on socio-economic criteria (water flows per hour of human activity and per hectare of land use), within the ecosystem view, on the role of water as a fund. We show how to check feasibility and viability of both water supply and water use. The grammar is implemented using practical examples.