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The treatment of water and wastewater provides numerous benefits to human health and the environment. Along with these benefits, however, come negative consequences associated with greenhouse gas (GHG) emissions, which until recently have been largely overlooked. Energy is required to produce water for consumptive uses as well as to collect and treat wastewater. Recent studies have begun to explore the total environmental impact of the water sector's energy use and GHG emissions. This research investigated a method for determining the impact of GHG resulting from municipal water consumption and wastewater disposal by customers in a specific geographic region. WATER AND ENERGYWater is indispensable to human health and well-being and crucial for sustainable development. The sustainability of water systems, however, is not limited to the quality of service provided. Approximately 4% of the electricity in the United States is used to move and treat water and wastewater (Appelbaum, 2002). The energy consumed in the municipal water cycle carries significant environmental consequences, most notably GHG emissions. Potable water is typically produced with nonrenewable energy resources; thus, the greater the embodied energy of the water, the greater the GHG emissions (The Brendle Group, 2007). Reduced consumption of electricity at treatment and pumping facilities equates to reduced operating costs and GHG emissions (Tripathi, 2007).Embodied energy refers to the quantity of energy required to manufacture and supply a product, material, or service to the point of use. In the water utility sector, embodied energy is the total amount of energy associated with the use of a given amount of water in a specific location (Wilkinson, 2000). It is the amount of energy consumed by all the processes associated with the production, delivery, consumption, and disposal of water.The US Department of Energy (DOE) and the US Environmental Protection Agency (USEPA) recently initiated programs aimed at assessing the nexus between water and energy (Sandia National Laboratories, 2006). Through the Energy-Water Nexus program, DOE is responsible for the development of technological products that will improve the nation's energy and water security. Eleven of DOE's national laboratories and the Electric Power Research Institute are investigating energy use by water-related systems and processes (Klein, 2005). USEPA is also investigating the relationship between water and energy consumption. In a 2008 memorandum to USEPA regional administrators, Benjamin H. Grumbles, assistant administrator in USEPA's Office of Water, promoted energy efficiency for the water sector (Grumbles, 2008). Some of the agency's efforts include adoption of environmental management systems, ENERGY STAR program additions such as water utility energy-tracking tools and a carbon footprint calculator, and use of Clean Water and Drinking Water State Revolving Funds to advance energy efficiency. USEPA has also developed a step-by-step workbook to help utilities ensure a sustainabl...

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Inflow and infiltration (I/I) associated with sanitary sewer pipeline and manhole defects have been known to cause unnecessary treatment expenditures. It is estimated that 10% or more of treated wastewater sources can be attributed to extraneous I/I. This paper documents an optimization model that analyzed costs and benefits of reducing the amount of I/I through selected rehabilitation methods recommended following a closed‐circuit TV inspection over a 20‐year planning horizon. An integer program was formulated using the General Algebraic Modeling System to optimize the sewer rehabilitation schedule and present value costs of repairs and I/I treatment. Results of a detailed analysis and the optimal rehabilitation schedule for a subshed of the Little Huntington Creek sewer system in Fairfax County, Virginia, are presented.