The aim of this study is to present a new technology based on the hydrocyclone concept capable of efficiently and cost effectively separating water and oil from bilge water for vessels below 400 GT. Laboratory tests showed that polluted waters treated by EcoBilge present oil levels of less than 1.7 mg/dm 3 . This signifies a contaminant concentration which is about 9 times lower than that allowed by MARPOL, representing an overall efficiency rate of above 99.