Methodologies for Successful Implementation of Smart Irrigation Controllers

Abstract

Studies have shown minimal impact by smart irrigation controllers when installed indiscriminately, but targeting overirrigators increases the water conservation potential. The objective was to evaluate different methodologies defining residential overirrigators. Two independent smart controller studies were conducted by utilities in Hillsborough County [Hillsborough County Water Resource Services (HCWRS)] and Orange County [Orange County Utilities (OCU)], Florida. In HCWRS, the cooperators qualified when irrigation was in the top 50th percentile of potable water users in the county. Additionally, the 21 cooperators were located in three cities determined as having high water use relative to other cities in the same area. In OCU, 132 cooperators received smart controllers when frequently irrigating more than 1.5 times the gross irrigation requirement (GIR). Actual ratios of historical average irrigation to the GIR ranged from 1.45 to 2.37 in HCWRS and 6.04–8.33 in OCU. As a result, cooperators in OCU showed significant reductions in irrigation with a return on investment of 4–14 months compared to HCWRS with a payback period of 17–27 months despite higher water rates and larger irrigated areas in HCWRS. Using the GIR as a benchmark proved to be a better method than using utility-wide percentile ranges of irrigation application to target homeowners for smart controllers to ensure irrigation reductions. Smart controllers are recommended for homeowners who average two times the monthly GIR for at least three months per year over at least three years when implemented in conjunction with relatively well-maintained irrigation systems. Water savings were guaranteed when ratios averaged more than six using the same frequency standards. Additional requirements for successful implementation include site-specific programming and providing basic knowledge to the homeowner.