This essay defines the concept of water security and explores the implications of the eternal pursuit of it. I will describe how water security is perceived by wealthy and by poorer nations, the tensions that arise from these differing views, and how these tensions are being resolved in a world in which the geography of economics and power is changing rapidly. I outline a few iconic cases of how societies have built institutions and infrastructure to deal with both floods and droughts. The essay assesses the effects of changes in climate and land use systems, and the differing reactions to the new perception of “nonstationarity”: the idea that these systems are less predictable than they have historically been. The essay concludes with some reflections on the challenges of educating young people seized with passion for the issues of their generation but who may have difficulty taking a long view of water security. Many have been taught about the environmental ravages wrought by water infrastructure, but few understand how these same infrastructure and institutions underpin the water security that the United States has achieved. Similarly, we teach the next generation too little about the remarkable contributions of “thinking practitioners”: experts who are also involved in policy-making and planning–whose work underpins the food, water, and energy security of their societies.