50 shades of gray

The Environment
The shipping and cruise industry must limit plastic pollution from grey water waste streams with the same regulatory control it has in place for sewage, says ACO Marine.
Grey water, that is to say domestic waste other than sewage, is largely unregulated. Yet it can form the larger percentage of water discharged overboard by ships. On the other hand, sewage, which is arguably less environmentally harmful, is subject to very stringent regulatory control.
Grey water is defined as waste water from domestic or commercial sources that has not come into contact with toilet waste – typical sources of grey water are bathrooms, kitchens and laundry operations. Black water – sewage – is tightly regulated, by IMO and other bodies. But there are no international regulations for grey water discharge, and this is seen by many as a significant omission from the MARPOL convention.
There is a point of view that grey water is potentially more environmentally harmful than sewage. Black water, after all, is basically organic. But grey water can contain oils, fats, detergents, chemicals and greases, not to mention plastics. Read on thanks to the Maritime Executive.