Emmett Institute on Climate Change & the Environment

Drops of Energy

Conserving Urban Water in California to Reduce Greenhouse Gas Emissions

Ethan Elkind


Water use means energy use. The state pumps and treats water and consumers use water in energy-intensive ways, such as through water heating and pressurizing. Consequently, the consumption of water in California requires approximately 20 percent of the state’s electricity, 30 percent of its non-power plant natural gas, and 88 million gallons of diesel fuel annually. The greenhouse gas emissions associated with water-related energy consumption total more than 100 million metric tons of carbon dioxide-equivalent gases, while the burning of carbon-based fuels to power the state’s water infrastructure releases particulate matter that can cause asthma and other health effects. Conserving water therefore means conserving energy and limiting pollution.

Water conservation is also critical as an adaptation strategy in an era of climate change. Climate models predict – and the state has already begun experiencing – altered precipitation patterns, dwindling snowpack, and unpredictable water supplies. In addition, rising sea levels from global warming and glacial melting threaten to inundate coastal groundwater supplies and sever critical links in the state water infrastructure. As a result, the state’s residents will need to make better use of less water.

Because not all types of water use have the same impact on energy use, the suite of conservation strategies that may work best for agricultural water use may look different from those appropriate for urban water use. This paper focuses on urban water use, defined as usage by residents, non-farm businesses, industries, and municipalities. According to the California Energy Commission, urban water use consumes more than 70 percent of the energy associated with water supply and treatment and almost 80 percent of the energy (electricity and natural gas) associated with end-uses of water.

Barriers to urban water conservation include lack of financial incentives, insufficient data on consumption levels, lack of consumer awareness, and lack of water efficiency funding. This paper discusses short- and long-term measures that California should implement to overcome these barriers.