Water and energy are closely interconnected and highly interdependent. Trade-offs need to be managed to limit negative impacts and foster opportunities for synergy. Water and energy have crucial impacts on poverty alleviation both directly, as a number of the Millennium Development Goals depend on major improvements in access to water, sanitation, power and energy sources, and indirectly, as water and energy can be binding constraints on economic growth - the ultimate hope for widespread poverty reduction. This fifth edition of the United Nations World Water Development Report (WWDR 2014) seeks to inform decision-makers (inside and outside the water and energy domains), stakeholders and practitioners about the interlinkages, potential synergies and tradeoffs, and to highlight the need for appropriate responses and regulatory frameworks that account for both water and energy priorities.