Water demand management (WDM) was reconceptualized as part of a social innovation framework, understood as a conservation culture that included efficient water consumption. This social innovation framework exposed WDM to new questions about WDM practitioners' social networks and knowledge. These questions have been under explored in conventional WDM efforts and research. The research was also an attempt to reconcile the extensive WDM knowledge and the failed, or failing, programs. The research goals were to identify and assess individuals' tacit WDM knowledge and to examine the influence of WDM practitioners' social networks. The objectives were: (1) to map the regional WDM network structures; (2) to evaluate the transmission of WDM information, beliefs and values; and (3) to identify intervention opportunities using the social networks and tacit knowledge. The field research included data from Namibian, Ontario and South African municipalities. The results were that, first, significant commonalities underpin countries' water conservation and efficiency problems under vastly different socio-economic and environmental conditions; second, social networks are critical to WDM policy and program implementation; third, the influence of tacit knowledge is underestimated in the water-management process; and fourth, there is an interaction effect between social networks, tacit and explicit knowledge that contributes to WDM policy and program processes. The methodology used for capturing practitioners' tacit knowledge, while subject to revisions, will also be a useful tool for other qualitative resource management studies. These findings suggest multiple implications and recommendations. For theory and research development, WDM can be understood as part of a social innovation, rather than merely a technical innovation. This reconceptualization would require changes in how we use decision makers' tacit knowledge and support social networks for information exchange. In practice, these research findings suggest new ways to alleviate implementation barriers in resource policy and improve program sustainability.