Analysis of Fixture Efficiency and Behavioral Factors of Indoor Residential Water Use of Single-Family Households

This study examines indoor water use patterns in single-family households by analyzing three key aspects: commonalities and differences between household water use categories, the relative importance of fixture efficiency versus behavioral factors in explaining water use and its differences between households, and the effects of weather, house characteristics, and household size on efficiency and behavioral factors. Using unprecedented high-resolution smart meter data from 33,435 households across 39 major US cities, we find distinct geographical clustering of high water-using households in southwestern, southern, and north-central regions of the US, with these households possessing more water-intensive appliances for indoor water and air quality management. In contrast, low water-using households cluster in coastal areas, particularly California. While behavioral factors explain most variation in total per capita indoor water use, fixture efficiency better differentiates between high and low water-using households, particularly around shower, toilet, and clothes washer end uses. We find significant economies of scale in both total per capita water use and specific behaviors, especially in toilet and shower uses, with per capita consumption decreasing as household size increases. Weather variations within cities significantly impact water use behaviors, particularly around toilet and shower end uses. These findings suggest that sustainable urban water management strategies should combine targeted fixture efficiency improvements with behavioral interventions, focusing especially on high water-using households and specific uses where the greatest conservation potential exists through both technological and behavioral changes.