Abstract The technical challenges regarding re-injection of produced water into tight oil reservoirs are discussed based on commercial experience. This paper demonstrates a successful case study based on a project that launched in 2005. The objective was to treat 320 m3/day of produced wastewater for tight oil reservoir re-injection. The effluent requirements were less than 1ppm oil, less than 1ppm TSS, and less than 0.8 micron particle size. The performance during the past 5 years of operation will be reviewed. Due to the unique composition of the influent water and very strict treatment requirements, this process was designed to overcome significant technical challenges. The process includes dissolved air flotation, micro-media filtration and UF membrane technology. This paper discusses the process configuration with an emphasis on actual operating results. The improvement in oil production and other significant findings will also be presented and reviewed.