Fresh, potable water is commonly used for landscape irrigation. Increasingly the green and high performance building codes that have been published and/or adopted impose significant restrictions on the use of potable water for landscape irrigation, and require the use of reclaimed water or other alternate sources of non-potable water to provide a majority of the water for landscape irrigation. Cooling towers, evaporative condensers, and fluid coolers provide a large supply of non-potable water through the blow-down generated by their operation. The chemicals that are often used to control scale, corrosion and bacteria in this equipment render the blow-down water unsuitable for use as a source of landscape irrigation water. However, non-chemically treated blow-down water is a potential source of landscape irrigation water since it only contains the natural mineral constituents found in the source make-up water (although at a greater concentration). This paper will review a study conducted in Southern California which had two objectives: First was to evaluate the direct application of non-chemically treated cooling tower blow-down water (using blends of blow-down water and potable water) on native California plants; the Second was to evaluate the potential savings in both water and energy by using cooling tower blow-down water for irrigation purposes. The conclusion of this study indicates that there was no significant difference in growth between those plants irrigated with 100% blow-down water compared to those plants irrigated with 100% potable water (or compared to those plants irrigated with a blend of blow-down and potable water). The study further quantifies the regional water and energy savings which can be achieved through the use of cooling tower blow-down water for landscape irrigation.