Due to the non-availability of Freon, there is need for an alternative method to measure the concentration of hydrocarbons in the effluent from oil water separators in use in the oil industry today. Current methods use solvent extraction and IR analysis of water samples. In this paper we present an alternative method, which does not use any solvents and can provide in-situ analysis of the hydrocarbon concentration in water. This method is based on FCI Environmental Inc.'s fiber optic chemical sensor (FOCS) technology. It provides accurate and reliable data to improve overall water processing on platforms. The instruments have been extensively tested by a number of companies on their platforms in the Gulf of Mexico and the North Sea. There are now over 120 instruments being used in the Gulf as an alternative to solvent extraction.