The discharge of raw sewage into the sea can create a health hazard, while in coastal areas sewage can also lead to oxygen depletion and an obvious visual pollution.
MARPOL Annex IV, as adopted in resolution MEPC.115(51), which entered into force on 27th September 2008, applies to ships on international voyages which are:
- 400gt and greater; or
- Less than 400gt when certified to carry more than 15 persons, which includes passengers and crew
The effluent standards and performance tests, as adopted in resolution MEPC.159(55), which entered into force on 1st January 2010, applies to ships having a sewage effluent plant installed or delivered and ships with a keel laid date on or after 1st January 2010.
Ships with a keel laid date and ships with an existing sewage effluent plant before the 1st January 2010, will require the plant certified to either the 1976 standards contained in MEPC.2(IV) or an applicable national specification.
For vessels visiting countries that have ratified to MARPOL Annex IV, these vessels will need to demonstrate compliance with the regulations, with the relevant certification (ISPPC).