“…As a scientific theory, it can be used to describe, explain, predict, and control [8] water reuse through feedback and learning [9,10] systemically as part of a broader ecosystem, and systematically by exploring the innumerable pathways within it. Ontological frameworks have been used to study river water sharing [11], national healthcare policies [12][13][14][15][16], design thinking [17], public health informatics [18], local climate change [19], and other domains. In the following paper, we (a) present an ontology of water reuse strategies based on the present definitions of water reuse, (b) discuss how it can be used as a comprehensive, national research design framework, and (c) delineate its implications for research on, policies for, and the practice of water reuse.…”