“Wat-er” They Irrigating: Characterizing Irrigation of Individual Residential Water Customers

Abstract

Irrigation can account for a substantial portion of a home's water use, and reductions in irrigation can have a large water conservation impact. This project provides an improved understanding of residential irrigation practices for the purpose of assisting utilities in planning and managing potable water demand. Customers are classified into groups of occasional, low, medium, and high irrigators. All customer groups were compared to a planning design standard. Monthly potable combined (indoor and irrigation) water billing records, property appraiser data, daily weather data, and U.S. Census data for Northwest Hillsborough County in Florida were used for this analysis. Irrigation applied per unit area was estimated by subtracting estimated indoor use from total water use, then dividing by the estimated irrigated area. Theoretical gross irrigation required was calculated using an irrigation efficiency and a daily soil-water balance that included weather and soil inputs at each customer's parcel. Ratios of irrigation applied to irrigation required were used to classify customers into irrigating groups. The majority of customers were classified as occasional irrigators (69%), followed by low irrigators (19%), and medium and high irrigators (6% each). Low, medium, and high irrigator groups all had potential for reducing irrigation without compromising landscape quality. The demand of the high irrigating group exceeded the requirement by 623 mm/year (92%).