It has been demonstrated that membrane technology can reduce the oil content of produced water as it comes off separators or hydrocyclones to below 1 ppm, which satisfies even the most stringent environmental standard onshore as well as offshore. The main capability of membrane technology is to remove oil from produced water without altering the mineral content using special designed membrane to allow for conventional disposal or reinjection in onshore situations and for overboard disposal in offshore situations. If required, the permeate from the membrane can be softened using a NF membrane, which will remove minerals contributing to hardness in the water. This has proved to be expedient in cases where water flood is applied and where the formation tends to be plugged by mineral precipitation.