Residential Irrigation Water Use in Central Florida Melissa B. Haley 1 ; Michael D. Dukes, P.E. 2 ; and Grady L. Miller 3 Abstract: Automatic inground irrigation is a common option for residential homeowners desiring high-quality landscapes in Florida. However, rapid growth is straining water supplies in some areas of the state. The first objective of this study was to document residential irrigation water use in the Central Florida ridge region on typical residential landscapes T1. The second objective was to determine if scheduling irrigation by setting controllers based on historical evapotranspiration ETT2and reducing the percentage of turf area combined with setting the controllers based on historical ET T3would lead to reductions in irrigation water use. The time frame of this study was 30 months beginning in January 2003. Irrigation accounted for 64% of the residential water use volume over all homes monitored during this project. The T1 homes had an average monthly water use of 149 mm/ month. Compared to the T1 homes, T2 resulted in a 30% reduction 105 mm/month, and T3 had a 50% reduction 74 mm/monthin average monthly water use. Average monthly water use was significantly different p 0.001across the three irrigation treatments. Setting the irrigation controllers to apply water according to seasonal demand resulted in significantly less irrigation water applied. In addition, increasing the proportion of landscape area from 23% T1 and T2ornamental plants irrigated with sprinklers to 62% and irrigated with micro-irrigation T3resulted in the largest reduction in irrigation water applied. Compared to T2 where only the irrigation controllers were adjusted, this additional decrease in irrigation water applied was a result of low volume application on only a portion of the landscaped beds where irrigation is only applied to the root zone of plants. DOI: 10.1061/ASCE0733-94372007133:5427 CE Database subject headings: Residential location; Irrigation; Water use; Landscaping; Irrigation scheduling; Florida. Introduction Irrigation systems are common in many residential communities built in recent years or are currently under construction in Florida due to the high-quality landscapes that are typically installed. Turfgrass is a key landscape component, and normally the most commonly used single type of plant in the residential landscape. Although Florida has a humid climate, the spring and winter are normally dry. The average annual precipitation for the Central Florida ridge is approximately 1,270 mm, with most of this in the summer months June through August. The spring months March through Mayare typically the driest USDA 1981. This region is also characterized by sandy soils with a low water- holding capacity; therefore, storage of water is minimal. The dry spring weather and sporadic large rain events in the summer coupled with the low water-holding capacity of the soilmake irrigation necessary to ensure high quality of landscapes desired by homeowners. Residential water use comprises 61% of public-supply water withdrawals Fernald and Purdum 1998. Public supply is the second largest use 43%of the groundwater withdrawn in Florida, after agriculture. Between 1970 and 1995, public-supply water withdrawals increased 135% Fernald and Purdum 1998 and Florida consumes more fresh water than any other state east of the Mississippi River Solley et al. 1998. The current population in Florida of over 16 million is pro- jected to exceed 20 million by 2015 USDC 2001. Due to drought conditions in the past few years, some municipali- ties within the St. Johns River Water Management District SJRWMDhave limited residential irrigation to twice a week. Residential irrigation is prohibited between 10 a.m. and 4 p.m., whether the water is from public supply, domestic self-supply i.e., wells, or surface water SJRWMD 2005. Irrigation outside of these hours is thought to reduce evaporative and wind losses. The irrigation systems used by the households in this region typi- cally include stationary spray heads and gear driven rotor sprin- klers for the turf and landscape. The SJRWMD has implemented rain sensor rebate programs and media programs to encourage outside irrigation water conservation efforts. Several research projects regarding residential irrigation water use were found in the literature indicating that irrigation water in residential landscapes is often excessively applied. Barnes 1977 found residential irrigation rates ranging from 122 to 156% of seasonal evapotranspiration ETrates in two Wyoming cities. A study using soil moisture sensors to control residential or small commercial irrigation systems resulted in 533 mm used for irri- gation, compared to the theoretical requirement of 726 mm Qualls et al. 2001. Aurasteh et al. 1984compared residential solid set and movable systems in Logan, Utah. Analysis of the application efficiency of these systems showed that the average water application efficiency was about 30% for hand-move and 1 Research Coordinator, Agricultural and Biological Engineering Dept., Univ. of Florida, P.O. Box 110570, Gainesville, FL32611. E-mail: mhaley@ifas.ufl.edu 2 Associate Professor, Agricultural and Biological Engineering Dept., Univ. of Florida, P.O. Box 110570, Gainesville, FL32611 corresponding author. E-mail: mddukes@ufl.edu 3 Professor, Turfgrass Science, North Carolina State Univ., P.O. Box 7620, Raleigh, NC 27695-7620. E-mail: grady_miller@ncsu.edu Note. Discussion open until March 1, 2008. Separate discussions must be submitted for individual papers. To extend the closing date by one month, a written request must be filed with the ASCE Managing Editor. The manuscript for this paper was submitted for review and possible publication on December 17, 2005; approved on June 8, 2007. This paper is part of the Journal of Irrigation and Drainage Engineering, Vol. 133, No. 5, October 1, 2007. ©ASCE, ISSN 0733-9437/2007/5-427–434/ $25.00. JOURNAL OF IRRIGATION AND DRAINAGE ENGINEERING © ASCE / SEPTEMBER/OCTOBER 2007 / 427