Quantifying Replacement Rates From Indoor and Outdoor Urban Water Conservation Incentives in California

In the United States, to promote water conservation, water agencies can offer rebates and incentives for adopting efficient fixtures, appliances, irrigation systems, and low-water landscapes. Limited research has evaluated the prevalence of rebate programs and the rates of replacement achieved by the programs. Using a statewide survey of program offerings and a database of over 1.78 million rebates in California from 2009 to 2020, we investigate two questions. First, what is the prevalence of urban water conservation programs and what activities do they fund? Second, at what rate do programs implement efficiency measures and how do rates vary across years? Results indicate that approximately two hundred agencies in California have incentive programs for customers and many also have education and outreach programs. Rebates for toilets, clothes washers, irrigation controllers, and turf replacement are prominent. The average annual rates of replacement from 2011 to 2020 differ across regions and spiked during drought. Annual replacement rates of toilets ranged from 0.1% to 2%, but rose to as much as 5% in years with drought. Average annual replacement rates for clothes washers, turf replacement, and irrigation controllers were lower (less than 1%). The presented approach offers insights for utilities to use in conservation planning and demand forecasting.