Drinking water and wastewater systems account for approximately 3-4 percent, equivalent to approximately 56 billion kilowatts (kW), or \$4 billion, of energy use in the United States, adding over 45 million tons of greenhouse gases annually. Further, drinking water and wastewater plants are typically the largest energy consumers of municipal governments, accounting for 30-40 percent of total energy consumed. Energy as a percent of operating costs for drinking water systems can also reach as high as 40 percent and is expected to increase 20 percent in the next 15 years due to population growth and tightening drinking water regulations.
The good news? Studies estimate potential savings of 15-30 percent that are "readily achievable" in water and wastewater plants, with substantial financial returns in the thousands of dollars and within payback periods of only a few months to a few years.