This study incorporates the energy demands of water abstraction, treatment, distribution, and post-use wastewater treatment into the Global Change Analysis Model, an integrated human-Earth systems model, and analyzes a range of scenarios that estimate the future evolution of this demand of energy. The study complements research on historical and future water-for energy, and builds on bottom-up estimates of historical energy-for-water (EFW), by integrating EFW into nation-level energy statistics, where EFW is normally categorized with other energy use in the commercial and public services, industrial, agricultural, and/or electric power sectors. This development allows more resolved projections of future energy demands in general, and in this study, allows for assessment of the energy implications of improvements in water access and water quality that are consistent with the sustainable development goals (SDGs). In our baseline scenario, EFW increases by 2.6 times from 2015 to 2050, and in the SDG scenario with enhanced water access, standards for treatment of wastewater, and irrigation, the consequent EFW demands quadruple from 2015 to 2050. The study highlights the value of integrated, multi-sector analysis in quantifying the future impacts of the SDGs and other aspirational targets.