This paper discusses sixteen instances of radical water policy change across the globe. The key question we seek to answer is about the role of individuals in such transitions. We call these individuals 'policy entrepreneurs' and we suggest that they can affect transitions through a set of strategies, such as idea development, coalition building, the detection and exploitation of windows of opportunity, network management, and venue shopping. Our empirical analysis shows that individuals do contribute to transitions. They do so in collectives, dividing tasks over various members. The way in which they manage to affect transitions depends, at least partly, on the institutional setting they operate in. Some national policy systems offer better opportunities for centralized direction (and thus top-down pattern of transitions) whilst other systems offer better chances for bottom-up change. In either case, change has to be prepared for before windows of opportunity open. One way to prepare change is to instigate pilot projects, showing the feasibility of other approaches to water management. Policy change is a political game: networks must be built, issues need to be framed strategically, forums manipulated or by-passed, and strategies adjusted to the peculiarities of the institutional system the entrepreneur is working in. © IWA Publishing 2011.