Natural resource management has changed profoundly in recent decades emphasizing new legislation that transfers responsibilities to local user groups. In this article, I follow changing water policies to Namibia and show that the enactment of policy in local institutions deviates from community-based natural resource management (CBNRM) blueprints and design. To understand why, I examine the theoretical premises of CBNRM. CBNRM is informed by rational choice theory which isolates economic transactions (e.g., sharing water) and assumes that people design institutions for a specific good. However, in the communities I study ethnographically, people depend on sharing multiple resources. To better understand how the degree of sharing and institutional overlaps matter, I explore empirically the concept of institutional multiplexity. Institutional multiplexity describes the number of transactions between two households in a social network. The results reveal that almost all social networks are institutionally multiplex. Institutional multiplexity implies that people cannot separate the sharing of water from sharing in other domains. Institutional multiplexity hinders the implementation of design principles such as fixing boundaries, sharing costs proportional to use, and formal sanctioning. However, it also opens other means for governing nature through social control. Keywords: Social networks, Social network analysis, Natural resource governance, CBNRM, Water, Africa.