MARPOL Annex IV Sewage Discharge
Minimum distance from land and rate/speed limits for sewage discharge per MARPOL Annex IV.
Minimum distance / rate
≥ 12 nm from nearest land; moderate rate while under way at ≥ 4 knots
Speed check
Speed ≥ 4 kn - compliant for untreated / comminuted
Formula, assumptions, and limits
$$\text{Distance} = \{12 \text{ nm (raw)}, \; 3 \text{ nm (comminuted)}, \; 0 \text{ (STP)}\}$$
MARPOL Annex IV Reg 11 requirements. Passenger ships in designated Special Areas (Baltic) must discharge only through type-approved STP regardless of distance. Holding-tank capacity ≥ 4 days × POB × 70 L/p/day typical.
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| $Treatment$ | Raw / comminuted / type-approved STP | - | installation |
| $Speed$ | Under-way ship speed | kn | log |
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