Effective management of the world's water resources is considered to require access to credible and reliable data and information regarding the state of the resource, and how it is affected by water use and development, land use practices and climate change ( Water resources data and information exchange is a key principle of the growing global normative framework for transboundary waters that shapes international law (Conca et al. 2006). Data and information exchange is an important design principle associated with the effectiveness of institutionalised cooperation (Zawahri 2008;Stinnett and Tir 2009). Joint water resources data and information gathering can alleviate disputes over data and prevent broader conflict (Bernauer and Kalbhenn 2010). Increasingly, using data and information to understand complex problems is seen as a key component of the successful governance of common pool resources and adaptive management strategies (Dietz et al. 2003;Raadgever et al. 2008).The issue of access to data and information on transboundary water resources, i.e. basins and aquifers that are shared by two or more states, is particularly important given the potential for conflict. Despite international calls for data and information exchange in transboundary waters and for exchange of basinspecific evidence to support cooperative management, no systematic research has been undertaken to understand where, how frequently, or what water resources data and information are exchanged.