In 2017, the Global High-Level Panel on Water and Peace called for strengthening knowledge-based and data-driven decision making and cooperation for water, security and peace. The rationale is that having better data leads to better water management, not only because it allows for a better diagnosis of the problems and development of solutions, but also a common understanding of these data builds trust and constructive dialogues between the involved actors. This is especially true in transboundary waters, where data and information exchange become an important mechanism to develop a mutual understanding about the basin amongst the parties. Yet, the interplay between data, knowledge, and power should not be neglected. Issues regarding data ownership - and the models transforming data into knowledge - merit attention to understand the political dimension of data.