Water and Energy Nexus

What Is It?

State legislatures and natural resource managers in the past have addressed water and energy as two separate issues. But in reality, water and energy are very connected and sustainable management of either resource requires consideration of the other.

As the need for energy increases, the need for water also increases, and vice versa. With the growing human population, there is growing demand for both of these resources. It takes a considerable amount of water to produce energy for fuel production, cooling, and power production among other things. It also takes a large amount of energy to extract, treat, and transport water for household, commercial, and industrial uses. Coal, the most abundant fossil fuel, currently accounts for 42% of U.S. electricity generation, and each kWh generated from coal requires withdrawal of 25 gallons of water. That means U.S. citizens may indirectly depend upon as much water turning on the lights and running appliances as they directly use taking showers and watering lawns. At a minimum the United States uses about 520 billion kilowatt hours per year which is equal to 13% of the nation’s total electricity use—to pump, heat and treat water. Resource managers and lawmakers across the country are beginning to take a fresh approach to the management of water and energy.

According to the California Energy Commission water-related energy use in California consumes approximately 20 percent of the state’s electricity, and 30 percent of the state’s non-power plant natural gas. As cited by the U.S. Environmental Protection Agency, running the hot water faucet for 5 minutes uses about the same amount of energy as burning a 60-watt bulb for 14 hours. And in 2000 the United States Geological Survey proved that thermoelectric facilities used 195,000 million gallons of water a day, which represents half of all of the water withdrawn in the United States.

Case Studies


Nevada has enacted a statue that recognizes the importance of the nexus between water and energy, and addresses the misuse of water for generating electricity. Under statute § 533.372, for the public interest and the economic welfare of the State of Nevada, the State Engineer may disapprove any use of water if that water is going to be used to create energy, if that energy would be exported out of the State of Nevada. Through this statute, the state is attempting to value and protect water sources in the state for its ability to create energy as well as other uses. (more information)

Portland State University

At Portland State University the Sustainable Water, Energy, and Environmental Technologies (SWEET) Lab has come up with a system to monitor water use trends. The SWEET Lab is trying to demonstrate that continuous monitoring of water use and reuse is more effective than only doing spot checks and arbitrary surveys. They intend to show that this system can be more efficient in monitoring water trends, and in return will be more efficient in supporting energy conservation. (more information)

San Diego

A San Diego case study revealed that intensive use of water (especially the intensive uses like washing clothes and taking showers) consumes more energy than any part of the urban water transport and treatment cycle. This is unexpected since transportation is a much more obvious energy consumer, particularly in the heat of Southern California. This shows that reducing water use can be a powerful tool for saving significant amounts of energy. For instance, the study demonstrates that if San Diego relied on water conservation efforts instead of increasing water supply from Northern California to provide the next 100,000 acre-feet of water, it would save enough energy to provide electricity for 25 percent of all of the households in San Diego. (more information)

More Information