Assessing Residential Outdoor Water Conservation Potential Using Landscape Water Budgets

Abstract

Landscape water budgets provide a benchmark of efficiency in residential outdoor water consumption, as well as a means of assessing overirrigation and possible water savings through conservation. This study investigates outdoor water conservation potential by analyzing trends, patterns, and drivers of overirrigation across 14,300 single-family residential customers in a central Texas city over a 5-year period (2015–2019). Customers exceeding their budgets were categorized using a bivariate framework based on temporal and quantitative measures of overirrigation. Between one-third and two-thirds of the customers exceeded their budgets during at least 1 month of the growing season, wasting an average of 423,000 m3 of water annually. Approximately 10% of customers contributed 56% of the total overirrigation during the study period. Overirrigation occurred throughout the growing season, but the number of customers and total volume wasted were highest in the fall months. Both overirrigation frequency and the amount wasted per unit of area tended to increase with property market value and decrease with landscape size. The methods and findings presented in this study can help water utilities evaluate potential outdoor water savings in their service areas and identify candidate customers for conservation interventions, such as landscape irrigation audits and educational workshops on efficient landscape watering.