 All OWS equipment, new or old, can, in a laboratory setting, separate oil and water, do so automatically, and produce clean water for discharge overboard that contains no more than 15 parts per million oil.OWS equipment is approved by testing it with specific cocktails of mixed oil and water.Initially these combinations were very simple, basically no more than a mixture of clean water and diesel fuel, but they have become more sophisticated under MARPOL MEPC 107(49).