Reliable, high-quality water services are a substantial component of a state’s or country’s energy consumption profile. Although the water–energy nexus has received much attention in the past few years, relatively little work has addressed water systems’ energy use, their potential for energy savings, or their empirical results of energy management. This paper surveys the literature on theoretical energy savings in water systems and compares the estimates with the outcomes of numerous case studies where water systems undertook energy efficiency projects and/or programs. The results in practice confirm that the theoretical estimates are indeed achievable; annual energy savings of 10 to 30 percent are typical among water utilities that pursue energy management. These savings come by capital projects, operational changes, and intra-agency inter-agency coordination to deliver water by the most energy-efficient path. Such solutions often help improve hydraulic performance and water quality, showing that energy management is cost-effective, prompt, and synergistic, a critical step in advancing sustainable water supply.