Current environmental regulations require that ships can not discharge bilge water containing >15 parts per million (ppm) oil. Defense missions include operations that generate significant amounts of bilge water; a consistently performing treatment system is paramount to sustain these missions and operations. Bilge water is a highly complex wastewater containing various organic and inorganic contaminants in which the oil may exist in several phases, each behaving differently in conventional oil water separation treatment. Due to the nature of this oily phase, a single treatment method can not efficiently treat bilge water to meet these regulatory limits. A series of process steps should be employed to treat each of the oil phases in order to achieve <15 ppm in the final effluent in accordance with international maritime, federal, and defense discharge requirements. Various treatment technologies and systems are assessed in terms of their ability to separate oil from water. A qualitative assessment of performance criteria, advantages, and disadvantages of these various technologies and systems was conducted to determine theoretical process trains for simulated bilge water types.