Grey water discharge from a ship.

BIMCO addresses the grey area of grey water

Published: 09 December 2021

Grey water is an often disregarded emission to the sea from ships but presents a potential source of both contaminants and microplastics. The new BIMCO position aims to clarify a way forward for the shipping industry and defines how we will support our members wishing to take action to reduce their grey water footprint.

As they would in a home, the domestic activities of the crew onboard a ship generate used water that is discharged into the sea. Such used water generated via drainage from dishwater, galley sink, shower, laundry, bath and washbasin drains is termed grey water. The amount and contents of the grey water is thus directly related to the number of people on board a ship- with a container ship, for example, producing significant orders of magnitude less grey water than a large cruise ship.

Grey water is complex mixture containing a large variety of contaminants including bacteria, pathogens, detergents and more. More recently, grey water has been identified as a direct source of microplastics into the marine environment. With marine pollution in general and microplastics being issues which BIMCO seek to address we are ready to ensure action can be taken to reduce the impact of grey water and to ensure we can provide positive input should mandatory requirements be discussed at IMO.

Currently, MARPOL does not regulate grey water. There are, however, some national and regional regulations on grey water whilst others are in the process of being developed. These are usually specific either to passenger and cruise traffic (due to the high volumes of grey water generated) or/and in areas where additional environmental protection might be afforded such as sensitive sea areas. In addition to regulatory gaps for grey water there are operational and technological challenges. A limited number of ships have the capacity to collect and hold grey water for discharge and/or for subsequent treatment and fragmented piping and tank systems on most ships trading today cannot collect grey water for discharge to reception facilities ashore.

The new position addresses that there is a necessity to take instant voluntary action to reduce the impact of their grey water discharges.. BIMCO will work to support its members to address the issue in a proportionate and practicable fashion. Over the coming months we will be seeking to provide our members information on operational and technological solutions as well as ensuring we keep abreast of any regulatory developments.

We would be delighted to hear from any members interested in the topic.

Beverley Mackenzie


Dr. Bev Mackenzie

Head of Intergovernmental Engagement

London, United Kingdom