Households that conserve water through home water reports will be pleased to learn that they may be saving money on another utility bill. A new study, Spillovers from Behavioral Interventions: Experimental Evidence from Water and Energy Use, shows that when consumers are informed of their water consumption rates, not only do they conserve that resource, they become more energy efficient, as well.

In a first-of-its-kind study using a randomized controlled trial, researchers determined that programs that encourage consumers to conserve one resource end up reducing the use of other resources– a phenomenon referred to as a behavioral spillover. Using high frequency water- and electricity-use data to investigate the effects of home water reports on patterns of electricity use, researchers found that consumers saved as much as 1.5 to 2 percent of their expected electricity consumption in the summer months. This finding is novel not only because it shows that water conservation programs affect energy use, but also because the magnitude of the savings rivals that of the deployment of popular home energy reports that are focused exclusively on electricity efficiency.

“Some of the energy savings can be attributed directly to consumers’ actions to save water such as doing one less load of laundry or fewer uses of their dishwasher weekly,” said Katrina Jessoe, Faculty Affiliate of The E2e Project and Associate Professor at University of California, Davis. “But, as much as 75 percent of the energy savings we found is coming simply from consumer’s exposure to personalized water usage reports that may have resulted in people paying more attention to all of their utility bills.” In great news for grid operators, researchers also found that households participating in the water saving program tended to conserve energy between 3PM and 7PM in the summer, a timeframe that includes peak electricity demand hours both for residences in the study and the electric grid.

“The results point to the significant savings that can be gained if more utilities considered costsharing and collaborating on their conservation programs across resource types such as water and electricity,” said Gabriel Lade, Assistant Professor at Iowa State University. “When both the water and electricity savings are considered together, the cost to implement these programs becomes much more affordable.”

Researchers analyzed hourly water- and energy-consumption data and household attribute information from approximately 4,500 households randomly selected from a set of more than 7,300 households in Burbank, California.

This study was one of three that won The E2e Project’s 2016 Energy Efficiency Research Design Competition, funded by a generous grant from the Alfred P. Sloan Foundation. It was conducted by researchers at the University of California, Davis and Iowa State University.

Read the full working paper.

Read the policy brief.

To interview one of the authors, contact Jessica Lubetsky at Jessica_Lubetsky@berkeley.edu.