Several years ago, in the Asia-Pacific Water Development Outlook 2007, the Prime Minister of India stated that “…if all members of society can have adequate access to energy and water, many of the societal problems can be solved”. That statement is as true today as it was then. Energy and water are inextricably linked – we need “water for energy” for cooling, storage, biofuels, hydropower, fracking etc., and we need “energy for water” to pump, treat and desalinate. Without energy and water we cannot satisfy basic human needs, produce food for a rapidly growing population and achieve economic growth. And yet, today, 1.3 billion people lack access to electricity and some 800 million people get their water from unimproved sources. Many more consume water that is unsafe to drink. These are mostly the same billion poor, hungry and underprivileged human beings. Over the coming 30 years food and energy demands are expected to increase dramatically, yet we will depend on the same finite and vulnerable water resource as today for sustaining life, economic growth and our environment. When addressing the “energy and water” theme during 2014 World Water Week in Stockholm we shall take an overall “systems view” of how we develop and manage energy and water for the good of society and ecosystems – at local, national, regional and global levels – and avoid unintended consequences of narrow sectoral approaches. The “water, energy and food security nexus”, underpinning the green growth approach, will be central to the agenda. The energy and water theme will be addressed from two overall perspectives: the societal opportunities and challenges, and the cross-cutting issues. Efficient production and use of energy and water is essential in the national context to ensure basic needs and development opportunities for people. However, both energy and water transcend national boundaries, physically through transboundary waters and power grids, and economically through regional economic cooperation. Cooperation between nations increasingly focuses on sharing benefits, rather than water per se, with both food and energy as the primary, water-dependent goods to share. At the global level recurrent crises – energy, food, financial – illustrate systemic inter-dependence. Developing countries have serious challenges in achieving the Millennium Development Goals (MDGs) by 2015, and the close water, energy, and food interconnections need to be considered in formulating Sustainable Development Goals (SDGs) to follow the MDGs from 2015. Energy and water are critical factors in urban development. Rapidly growing cities depend on reliable energy and water supply, but must try to reduce demands, manage trade-offs and optimise resource use by reuse, recycling and generation of energy from waste, all in an integrated urban management context. For industrial development improved efficiency in the use, and reuse, of energy and water is essential to save on increasingly scarce resources and costs, for both production and waste management. An added driver is to strengthen corporate social and environmental responsibility through sustainable production. Research, innovation and technology development for improved energy and water efficiency are essential for such efforts. The energy-water linkage is not only about quantity, but also about water quality and pollution, related to pollutant discharge, to significant quantities of heated cooling water affecting surface waters, or to potential groundwater pollution due to energy-related geo-engineering activities, including fracking. Sharply accelerating demands for food and energy production place increasing pressure on the availability of water for vulnerable ecosystems and the biodiversity and human livelihoods they sustain. Energy production, be it hydropower development, biofuel production, shale gas exploitation or other forms of energy production, may have serious environmental and social consequences that need to be properly assessed and addressed. Climate change may affect the water system through increased variability, long term temperature and water balance changes and sea level rise, and is in many cases an added driver to be considered. Climate adaptation is primarily about water and land, but water resources are also critical for climate change mitigation, as many efforts to reduce carbon emissions rely on water availability. Because the water cycle is so sensitive to climate change, and because water is so vital to energy generation and carbon storage, we need to recognise the coherence between mitigation and adaptation measures. In ensuring this, and managing variability and environmental flow requirements, storage of both energy and becomes a critical issue, including water as a medium for storing energy. Storage may be required at all levels, from the household and village levels to major infrastructure in a transboundary settings, not least in developing countries. Such storage may be provided through investments in conventional infrastructure and/or in the restoration and management of natural systems. Unintended consequences of energy development for water, and vice versa, often have their roots in fragmented policies, e.g. energy subsidies in some parts of the world contributing to unsustainable groundwater overdraft through excessive pumping. The energy and water worlds seem to be divided between those who focus on technical solutions, and those who assume that the challenge is rather one of politics and governance. In taking a “systems view” energy and water policies need to be coordinated. In developing effective energy and water governance different characteristics and traditions prevail: while energy production most often is centrally managed, good water governance needs to include local, de-centralised planning and management in dialogue with affected stakeholders. For both, top-down needs to meet bottom-up governance. As evident when addressing the water, energy and food security linkages, real engagement of actors from other sectors is a pre-condition for success. For water the implementation of the Integrated Water Resources Management (IWRM) approach includes energy, but its role has not been sufficiently examined. In the energy sector policy choices, whether conventional or alternative, must depend on water resources availability and vulnerability. Both require stakeholder involvement in the entire chain from resource exploitation through regulation to consumption, including consideration of both energy and water in the food chain from “field to fork”. Poor and vulnerable stakeholders in developing countries require special attention, as does improved gender equality and youth participation. The economic value of energy varies in a changing market and may be difficult to assess for long term investments. For water, assessments of economic value must accommodate the fact that water is a public and social good, and access to safe drinking water has been declared a human right by the United Nations. At the same time, assessment of costs and benefits for different water uses needs to address gaps in knowledge of values linked to biodiversity and ecosystem services. However, when addressing benefit sharing, and likely energy and water markets, not least across boundaries, acceptable and reliable estimates are required. When it comes to financing and pricing the situation is equally complicated, due to the asymmetry, volatility and inter-linkages of energy and water prices, with energy mainly being priced on the market and water as a public good. Understanding of these inter-linkages, and their economic and financial implications, are necessary for both public and private decision-makers. Access to, and sharing of data and information, not least across jurisdictions and boundaries, is in itself a major challenge for water resources management. In transboundary settings it is often considered an issue of national security. The data and information challenge does not become easier when water and energy is combined. However, assessment of the inter-linkages and trade-offs for water from energy development, and vice versa, is strengthened greatly by an environment of dialogue, trust and full sharing of data and information between decision-makers and affected stakeholders, both public and private. It must also be flexible and adjustable to rapid change. Energy and water data and information may be made more accessible through mobile technologies. The complexity of decisions on water and energy development often calls for combined water- energy modeling as a basis for developing integrated decision support systems. In both sectors advanced models have been developed, and efforts to further combine and apply integrated water and energy modeling systems are underway. Such developments include hydro- and energy economics, ecological and hydrological effects, social criteria and economic tools to quantify trade-offs. In the final declaration “The Future We Want” from world leaders at the Rio+20 Summit in 2012 the chapter on energy contained no reference to water, and the water chapter did not mention energy. Clearly, whilst a lot of information about the waterenergy linkages has been developed, awareness and knowledge have not transcended sectoral boundaries at the administrative and political levels. The science-policy-people dialogue on water and energy needs to be improved based on increased “water and energy literacy” and improved efforts to communicate advances in science and good practice, and innovation in technology and management, to our political decision-makers. Meanwhile, political decision-makers need to set the agenda and framework for the science and technology to become policy relevant. In the developing countries in particular such efforts need to be associated with efforts to develop capacity at all levels to address these inter-linkages.