A Fuzzy-Set Qualitative Comparative Analysis of Potable Water Reuse Implementation Pathways.

The United States is facing increasing water scarcity challenges. Approaches that enable potable water reuse implementation are needed to increase supply and resilience. Therefore, we conducted a fuzzy-set qualitative comparative analysis after collecting data on 16 potable reuse projects using interviews, documentation, and field observations. We identified four generalized implementation approaches (i.e., success pathways); all shared the same causal conditions of committed interagency agreements, sufficient operator training, project leadership continuity, and positive media coverage. Three success pathways combined the shared causal conditions with low infrastructure integration burden, external public capital expenses funding, and one of multiple approaches for securing public acceptance: community spokespersons' local endorsement, a permanent demonstration/visitor center, or public education initiated 24 months before the implementation decision. The fourth pathway provides an implementation approach when infrastructure integration is complex and public funds are uncertain; it combined the shared causal conditions with internal/private capital expenses funding and public education initiated 24 months before the implementation decision. Further evaluating case knowledge also identified actionable guidance (e.g., onboard operators early to build confidence and earn certifications). This cross-case comparison's strategies, which include multiple context-specific success pathways, can be applied to successfully implement potable water reuse and increase high-quality drinking water supplies.