The key link between a valid design concept for energy efficient wastewater treatment and the realization of that goal is the treatment plant operator. His understanding of the processes and equipment systems and his ingenuity in dealing with changing conditions make energy conservation and recovery possible. He needs a grasp of the inter-relations between unit processes and their costs in dollars and energy so he can fine-tune the plant to optimize the use of our dwindling resources. All of the wastewater treatment plants in the United States consumed only about 0.17 percent of the nation’s electricity in 1977, but that amounted to approximately $300 million worth of energy! As this figure increased and energy supplies continue to dwindle, more emphasis is being directed toward energy conservation in plant design and operation. Since most treatment facilities depend largely on electricity as their source of energy, this paper will begin by defining in general how power rate schedules are set up. Treatment plant operators need to understand the methods used to compute the plant’s power bill so that they can direct their energy-saving efforts towards cost-saving as well. Examples of energy-conservation techniques used in various plants are described using generalized case examples. The operator’s role in optimizing the use of energy is the focus of these discussions, with emphasis on areas such as biological treatment, solids handling, and energy recovery. The intent of this presentation is that operators will relate these examples to situations in their own plants to aid them in devising programs for conserving energy.