Those responsible for water governance face great complexity. However, the conceptualisations of what comprises that complexity have been broad and inconsistent. When efforts are made to address the complexity in water governance, it is unclear whether the problems and the related solutions will be understood across the actors and institutions involved. This paper provides a review of the literature focused on global water governance to discern core themes that commonly characterise discussions of complexity. It then considers how the consequences of these issues are manifested at the local scale through an examination of empirical research of the Murray-Darling Basin Authority and the Prachinburi River Basin Committee. The results demonstrate that a history of a technical, depoliticised discourse is often perceived to contribute to complexity. The consequence is that when a severe ecological disturbance occurs within a river basin with poorly understood causes, few tools are available to support river basin organisations to address the political nature of these challenges. Additionally, a lack of clear authority structures has been recognised globally, but locally this can contribute to conflict amongst the 'governors' of water. Finally, a range of contested definitions and governance frameworks exists that contributes to complexity, but confronting the diversity of perspectives can lead to ethical dilemmas given that the decisions will affect the health and livelihoods of basin communities.