Graywater as an Alternative Irrigation Water Source for the Green Industries

The use of alternative irrigation water sources has become an imperative premise to green industry activities. Their dependence on high quality and ground, surface, and potable water supplies is endangered by severe and lengthy droughts and stiff competition from other extensive human uses and allocations, and scrutiny on the environmental impact of green industry activities. Landscape irrigation is the largest user of water in urban setting with reports suggesting it accounts for ≥ 50% of the total residential potable water use. Graywater—untreated water that comes from laundry washers, showers, and bathtubs, constitutes about 50% of the total household wastewater—has the potential for becoming a significant source for landscape irrigation. While studies from our group and others suggest laundry graywater effluents can be used to satisfactorily grow ornamental plants, there is concern over the long-term effects of graywater irrigation on the chemical, physical, and biological characteristics or urban landscape soils and their surrounding built and native ecosystems. We have established long-term landscape graywater irrigation studies on replicated landscape plots to evaluate these effects, and to serve as a demonstration and educational platform to provide answers and practical solutions to the potential use and management of residential graywater irrigation.