As offshore oil wells age, the increase of produced water challenges wastewater treatment systems.To ensure oil levels in the water are under the regulatory limit, it is important to do regular testing. Infrared is an accepted oil content measurement as it is least affected by changes in produced water composition. For industrial pretreatment of wastewater and public water treatment plants a simplified procedure for monitoring FOG discharges can avoid fines, sanitary sewer overflows (SSOs) and give on-site results in less than 15 minutes rather than waiting days or weeks for an off-site laboratory result.