🔍 Key Concepts

• MARPOL Annex IV distance-from-land requirements for sewage discharge • Difference between comminuted and disinfected sewage and untreated sewage • How discharge rules change inside vs. outside the 3–12 nautical mile zones

💭 Think About

• Think about what MARPOL Annex IV is mainly trying to protect when a ship is very close to the coast. Would it allow any kind of sewage discharge that could affect swimmers, fisheries, or coastal waters? • Compare what is allowed beyond 3 nautical miles with what is allowed inside 3 nautical miles. Is the regulation becoming stricter or looser as you get closer to land? • Ask yourself: if there is any doubt about environmental impact near shore, would MARPOL permit more types of discharge or fewer?

✅ Before You Answer

• Verify the exact distance limits in MARPOL Annex IV for comminuted and disinfected sewage discharge (3 nm vs 12 nm) • Confirm whether any treated sewage is allowed inside 3 nautical miles of the nearest land • Check if MARPOL makes an exception for disinfected sewage when closer than 3 nm, or if it treats all sewage the same within that zone