News 17 Sep, 2025 Grey Water Regulation: A Growing Environmental Compliance Challenge Marcus Winchester Loss Prevention Officer The Club has seen a recent spate of pollution incidents involving the discharge of grey water within territorial waters which fall outside of what is permitted by the local port state authority under national legislation. These incidents have resulted in detentions and fines from Port State Control.  Download PDF Grey water is defined as wastewater originating from domestic sources such as baths, showers, sinks, washing machines and other kitchen appliances on board. Grey water at present is not regulated under MARPOL Annex IV. Currently, MARPOL Annex IV explicitly excludes grey water from the definition of sewage. This creates a regulatory void that individual port states are increasingly filling with their own restrictions, as scrutiny around the discharge of grey water increases globally. This absence of international coverage has prompted numerous countries to implement their own local regulations. There is currently no MARPOL prohibition on the discharge of grey water by commercial shipping. However, there is an increasing frequency of nation states imposing their own national restrictions such as with the Turkish marine pollution law which prohibits discharge of grey water. Another example is the United States' Vessel Incidental Discharge Act (VIDA), which is expected to enter into force in 2026, that will further strengthen and consolidate various federal, state and local requirements relating to incidental discharges of grey water. This fragmented approach on a region-by-region basis creates an ever more complex compliance challenge for international shipping. Voluntary operational measures can significantly reduce contamination risks, including installing microplastics filters on washing machines and using phosphate-free, biodegradable products. Clear crew warnings and proper system maintenance are essential for preventing acc