How Much Water Does Turf Removal Save? Applying Bayesian Structural Time-Series to California Residential Water Demand

Abstract

California water utilities have invested historic amounts of money in turf rebates to incentivize customers to remove their turf grass and replace it with more water efficient landscaping. This study utilizes a data set of 545 unique singlefamily residential turf rebates across 3 California water utilities, totaling 635,713 square feet of converted turf grass to estimate the water savings from turf removal. Monthly water savings are estimated at the household level as the difference between actual usage and a synthetic control and then aggregated using a mixed-effects regression model to investigate the determinants of water savings. Analysis of turf removal at the monthly level is found to be critical for understanding the seasonal behavior inherent in outdoor water use. Mean predicted savings for single-family residential accounts are estimated at 24.6 gallons per square foot per year for the households used in this study.