This paper reviews the history and present status of a successful advanced recycled water treatment system in operation for more than 12 years in a major petrochemical plant. This pioneering project started with a water resources management study that identified an in-plant recycled water project that would be both environmentally and economically beneficial. Because of the relatively high total dissolved solids (TDS) of the water supplied from the water company, using highly purified recycled water to feed the plant’s deionization (DI) system would save 70 to 80 percent of the expensive DI regeneration cost and drastically reduce water and wastewater fees. A one-year pilot testing program confirmed the recycled water system’s technical feasibility and provided design criteria for the full-scale 6,600 cubic meters per day (m3/d) advanced treatment system, which includes the processes of chemical oxidation, granular media filtration, granular activated carbon (GAC) adsorption, ultrafiltration (UF), ultraviolet (UV), reverse osmosis (RO), and decarbonation. Over the past 12 years, more than 25 million m3 of purified water were recycled to feed the plant's DI system.