The Fischer-Tropsch (FT) process creates significant amounts of water. This FT produced water contains significant amounts of organic impurities. The invention provides methods of treating FT produced water. Surprisingly, it was discovered that the FT produced water could be successfully treated in a membrane bioreactor (MBR) according to relatively simple and more efficient steps; for example, by adjusting the pH of the water in the range of 4.2 to 5.8 or treating the FT produced water in a stripper where the distillate product stream and a reflux stream returning to the stripper have the same composition. In a related aspect, water compositions are described.