The new regulations will prohibit discharge of sewage into the sea at a distance of 12 nautical miles, or less, from the nearest land. Exceptions apply when the ship has an approved sewage treatment plant in operation or when discharging disinfected sewage using an approved system more than three nautical miles from the nearest land.

Under current thinking, it is assumed that the open oceans are capable of assimilating and dealing with raw sewage through natural bacterial action. Discharging raw sewage in shallower seas, however, can create health hazards and lead to depletion of oxygen in the water as well as visual pollution – a particular problem for countries with large tourist industries.

The revised MARPOL Annex IV will apply to new and existing ships of 400 gross tonnage and above or ships which are certified to carry more than 15 persons, engaged in international voyages.

Ships must be fitted with either a sewage treatment plant, a sewage disinfecting system or a sewage holding tank and will have to comply with the regulations by 27 September 2008.

David Hopkins

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