Oily water separator

An oily water separator (OWS) is a piece of shipboard equipment that allows a vessel's crew to separate oil from bilge water before the bilge water is discharged overboard.

Bilge water is an almost unavoidable product in ship operations. Bilge water that is generated in proximity to shipboard equipment (such as in the engine room) often contains oil and its direct discharge would result in undesirable transfer of waste oil to the marine environment. By international agreement under the MARPOL convention, most commercial vessels need to be fitted with an oily water separator to remove oil contaminants before bilge water is pumped overboard.

Oily water separator equipment has been a shipboard requirement since the 1970s but recently it has become evident that oily water separators have not been as effective as had been assumed, and alleged improper operation of this equipment by crewmembers (sometimes called the magic pipe) has resulted in criminal prosecutions in the United States and to a lesser extent in Europe.

See also

• API oil-water separator
• Wastewater treatment
• Magic pipe