Shipboard oily water separators are internationally mandated as engine room equipment and are intended to allow engine room crews to clean engine room bilge water prior to discharge into the world’s oceans. This equipment was mandated based on the assumption that uncleaned discharge of engine room bilge water would result in discharge of oil into the environment. Oily water separator equipment has now been installed aboard commercial vessels for over 30 years, but there is reason to question the actual effectiveness of this equipment. It has never been clearly established if oily water separators actually work to a level that enables crews to operate them in a reliable fashion.