MARPOL Annex IV - Sewage Holding Tank Capacity
Required black-water holding tank capacity from persons on board, daily generation rate and longest no-discharge segment.
Formula, assumptions, limits
V_tank in cubic metres, N persons, q litres per person per day, t no-discharge days, k reserve factor (typically 1.1 to 1.2). Default q is 50 L/person/day per IMO MEPC.115(51) commentary; cruise ships typically 65 to 90 L/person/day. The longest no-discharge segment is the worst-case time between reception facility access plus operations within 12 nautical miles of nearest land. Holding tank size is also constrained by ship structural and weight considerations.
Symbol legend
SymbolMeaningUnitSource
Persons on boardpersonssafety certificate Generation rate per personL/person/dayoperator estimate Longest no-discharge segmentdaysvoyage plan Reserve factormultiplieroperator policy Required holding capacitym³computed
In short
Required black-water holding tank capacity from persons on board, generation rate and no-discharge segment.