Water related problems such as floods, droughts, declining groundwater tables or polluted rivers have a major impact on numerous societies throughout the world. Despite these serious problems, policy makers seem to make scant use of the knowledge that is available with water experts. Conversely, water experts face the task of finding out how they should position themselves to ensure that their analysis contributes to policy making. The task for those water experts is further complicated by the fact that water resources management involves various parties, called actors. Each actor has its specific position and responsibility in policy making, its own interests and objectives and its own perceptions of the main problems to be addressed. Actor analysis offers a potentially promising tool to support water experts, as it can be used to investigate the multi-actor policy making setting in which water experts find themselves. This is likely to help water experts design and execute analyses that are relevant to policy makers. Actor analysis for water resources management provides insight into how actor analysis is done in practice. A model-based approach for actor analysis is developed and its use is described for cases in Egypt, Turkey, the Netherlands and the Philippines. The results of these four cases are used to examine to what extent actor analysis lives up to its promise for water experts. The findings shed light on the use of actor analysis in practice and its potential to help water experts in their interactions with policy makers. Policy analysts and water experts alike may find the guidelines on executing an actor analysis valuable, and the examples of applications inspiring to their daily tasks.