The competition between water and energy needs represents a critical business, security, and environmental issue, but has not yet received the attention that it merits. Energy production consumes significant amounts of water; providing water, in turn, consumes energy. In a world where water scarcity is a major and growing challenge, meeting future energy needs depends on water availability –and meeting water needs depends on wise energy policy decisions. This paper serves as an objective, non-partisan information source that motivates policy-makers, business leaders, investors, NGOs, and the general public to ask further water-related questions – and to probe critically into the responses they receive. We also seek to increase visibility of water-energy nexus implications on business (opportunities, supply chain costs/inefficiencies, and risks), security (food, military, and energy), and the environment (agriculture, forest, and climate). The water-energy nexus, along with its wide-ranging impact and the challenging questions that result, has earned a rightful place on the global policy agenda.