What Is MARPOL? A Guide to the Six Annexes

MARPOL Annex IV addresses pollution by sewage from ships.

It establishes requirements for sewage collection, treatment, storage and discharge, as well as certification and reception facilities. Applicable ships may use approved sewage treatment plants, comminuting and disinfecting systems or holding tanks.

 Learn more about: MARPOL Annex IV: Sewage Pollution from Ships | SeafarersHub

Annex V – Garbage from Ships

MARPOL Annex V regulates garbage generated onboard ships.

Its basic principle is that the discharge of garbage into the sea is prohibited unless specifically permitted. It covers food waste, plastics, domestic and operational waste, cargo residues and other types of garbage.

Garbage Management Plans, Garbage Record Books and placards are also required on applicable ships.

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Annex VI – Air Pollution from Ships

MARPOL Annex VI addresses air pollution from ships.

It regulates NOx, SOx, particulate matter, ozone-depleting substances, fuel oil quality and shipboard incineration.

Annex VI also contains important energy-efficiency and carbon-intensity requirements, including EEDI, EEXI, SEEMP and CII.

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MARPOL at a Glance

Annex I: Oil

Annex II: Noxious liquid substances in bulk

Annex III: Harmful substances in packaged form

Annex IV: Sewage

Annex V: Garbage

Annex VI: Air pollution

A simple way to remember them is:

Oil → Chemicals → Packages → Sewage → Garbage → Air

Why MARPOL Matters to Seafarers

MARPOL is not simply a collection of environmental regulations. Its requirements affect everyday shipboard activities, including machinery operation, cargo handling, waste management, pollution-prevention equipment and record keeping.

Effective compliance can be summarized through four connected elements:

Equipment + Procedures + People + Records

Understanding the six Annexes provides seafarers with the foundation needed to apply MARPOL correctly during everyday ship operations.

Conclusion

MARPOL is one of the most important international conventions for protecting the marine environment from ship-generated pollution.

Its six Annexes address oil, noxious liquid substances, harmful packaged substances, sewage, garbage and air pollution.

For seafarers, understanding what each Annex covers the first step toward effective environmental compliance is onboard.

References

International Maritime Organization (IMO). (2022). MARPOL: Consolidated Edition 2022. London: IMO.

International Maritime Organization (IMO). (2026). March 2026 Supplement to MARPOL Consolidated Edition 2022. London: IMO.

International Maritime Organization (IMO). International Convention for the Prevention of Pollution from Ships (MARPOL). IMO.

International Maritime Organization (IMO). (2024). International Maritime Dangerous Goods (IMDG) Code, Amendment 42-24. London: IMO.