Assessing Urban Residential Irrigation Performance Using a Water Budget Approach

Wasting water by excessive irrigation of urban residential landscapes is a ubiquitous problem. By reducing irrigation in excess of plant water needs, homeowners and cities save substantial quantities water. Although water utilities can use a variety of approaches to encourage customers to reduce their consumption, some residences may use water more efficiently than others. By understanding patterns of irrigation performance among customers, water utilities can develop more economical approaches for encouraging water conservation. Irrigation performance can be assessed by comparing outdoor water use with a landscape water budget. This requires an accurate estimate of irrigated landscape area, which can be difficult to obtain for citywide datasets. A bivariate approach using tax appraisal information is proposed, which can be applied in any county. Irrigation performance was assessed for 5,565 single-family residences by examining their conformance to monthly water budgets. Nonconformance was defined as outdoor water use exceeding the monthly budget volume. Large lots were found to overwater by significantly greater volumes than smaller lots. However, lots with smaller landscape areas tended to overwater more frequently and apply higher volumes per unit area. These findings suggest new management options for addressing consistently wasteful water use and improving efficiency