Energy is needed to accomplish many of these  activities. Comprehensive Data about the Energy Needed for the Urban Water Lifecycle Are Limited, However Energy Needs Are Influenced by Location-Specific Factors

Comprehensive data about the energy needed for each stage of the urban  water lifecycle are limited, and few nationwide studies have been  conducted on the amount of energy used to provide drinking water and  wastewater treatment services to urban users. However, specialists with  whom we spoke emphasized that the energy demands of the urban water  lifecycle vary by location; therefore, consideration of location-specific and  other factors is key to assessing the energy needs of the urban water  lifecycle. These factors include the source and quality of the water, the  topography of the area over which water is conveyed and the distance of  conveyance, and the level and type of treatment required. In  particular, according to several specialists, the EPRI studies are outdated. As a result, cities that rely on  groundwater as the source for their drinking water, such as Memphis,  generally use less energy for treatment than cities that rely on surface  water, such as Washington, D.C. The type of treatment process used at drinking  water and wastewater facilities also influences the energy demands of  providing drinking water and wastewater services to urban users. Certain Technologies and Approaches Can Reduce Energy Use, but Barriers Could Impede Their Adoption

Specialists we spoke with and studies we reviewed identified a variety of  technologies and approaches that can improve the energy efficiency of  drinking water and wastewater processes associated with the urban water  lifecycle, and determining the appropriate solution depends on the  circumstances of a particular system. Replacing less efficient equipment with more  energy-efficient equipment can reduce energy use. In  addition, leak detection technologies can identify leaks throughout water  systems, thereby reducing water loss and the related energy required to  pump and treat that “lost” water. For example, San Diego is implementing advanced metering  tools to better manage its system and to provide real-time information to  customers regarding their water use in order to help them make choices  that conserve water. Many specialists told us that, as a result, utilities may not be able to justify  the costs necessary to install energy-efficient equipment. Agency Comments

We provided a draft of this report to the Departments of Defense, Energy,  and the Interior and EPA for review and comment. DOE and EPA provided  technical comments that we incorporated into the final report as  appropriate. Appendix I: Objectives, Scope, and Methodology

Our objectives for this review were to describe what is known about (1)  the energy needed for each stage of the urban water lifecycle, and (2)  technologies and approaches that could lessen the energy needed for the  urban water lifecycle, as well as any identified barriers that exist to their  adoption. These specialists represented a variety of organizations, including drinki water and wastewater treatment facilities; state and local government  offices responsible for water or energy; officials from the EPA; researc from some of the Department of Energy’s national laboratories, such as  Sandia National Laboratory; university researchers; water and energy  industry representatives from groups such as the American Water Works  Association and the Water Research Foundation; and relevant  nongovernmental organizations, such as the Pacific Institute, a  nonpartisan research institute that works to advance environmental  protection, economic development, and social equity.
Why GAO Did This Study

Providing drinking water and wastewater services are two key functions needed to support an urban lifestyle. To provide these services, energy is needed to extract, use, and treat water and wastewater. As the demand for water increases, the energy demands associated with providing water services are similarly expected to grow. GAO was asked to describe what is known about (1) the energy needed for the urban water lifecycle and (2) technologies and approaches that could lessen the energy needed for the lifecycle and barriers that exist to their adoption. To address these issues, GAO reviewed scientific studies, government-sponsored research, and other reports and interviewed specialists from a variety of organizations, including drinking water and wastewater utilities; federal, state, and local government offices responsible for water or energy; and relevant nonprofit groups, about the energy needed to move, use, and treat water. GAO also selected three cities--Memphis, Tennessee; San Diego, California; and Washington, D.C.--as illustrative case studies to help understand the energy demands of the lifecycle in different areas of the country. GAO is not making any recommendations in this report. A draft was provided to the Departments of Defense, Energy (DOE), and the Interior, and the Environmental Protection Agency (EPA). DOE and EPA provided technical comments, which we incorporated as appropriate..

What GAO Found

Comprehensive data about the energy needed for each stage of the urban water lifecycle are limited. In particular, few nationwide studies have been conducted on the amount of energy used to provide drinking water and wastewater services, and these studies do not consider all stages of the lifecycle in their analysis. Specialists GAO spoke with emphasized that the energy demands of the urban water lifecycle vary by location. Considering location-specific and other key factors is necessary to assess energy needs. The specialists mentioned such factors as the topography of the area over which water is conveyed, the level and type of treatment provided, and the quality of the source water. For example, systems relying on groundwater as their source for drinking water generally use less energy than systems relying on surface water because groundwater usually contains fewer contaminants and, therefore, requires less treatment before distribution to customers. A variety of technologies and approaches can improve the energy efficiency of drinking water and wastewater processes, but barriers exist to their adoption. Installing more efficient equipment, adopting water conservation measures, and upgrading infrastructure are among some of the approaches that can decrease energy use, according to specialists GAO spoke with and studies GAO reviewed. For example, technologies to identify potential pipeline leaks throughout water systems can reduce water loss and the energy required to pump and treat that "lost" water. However, according to specialists, adoption of technologies and approaches to improve energy efficiency may be hindered by the costs of retrofitting plants with more energy-efficient equipment and competing priorities at treatment facilities, among other barriers.