Captain's Brief · Maritime Learning · 2 min read · Oct 18, 2026
Photo: LEE 003, CC BY 4.0, via Wikimedia Commons.
Sewage Treatment Plant and MARPOL Annex IV Discharge Rules
What is an STP, and where can sewage go overboard? Under MARPOL Annex IV, it depends on your system and your distance from land. Know the rules before a stopped plant becomes a detention. Source: MARPOL Annex IV, IMO MEPC.227(64).
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