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Adopted 14 February 1990, having regard to Article 13, Paragraph b) of the Helsinki Convention



RECALLING Paragraph C of Regulation 7 of Annex IV to the Convention on the Protection of the Marine Environment of the Baltic Sea Area, 1974, (Helsinki Convention), concerning the discharge of sewage,

RECALLING ALSO that the Marine Environment Protection Committee (MEPC) of IMO has adopted, at its sixth session, Resolution MEPC.2(VI) - Recommendation on International Effluent Standards and Guidelines for Performance Tests for Sewage Treatment Plants,

RECALLING FURTHER that the Commission has adopted, at its first meeting, a Recommendation concerning the application by the Baltic Sea States of guidelines for type testing and approval of sewage treatment systems,

RECOGNIZING the need for the standardization of the capacity calculation of sewage systems,

RECOMMENDS that Governments of the Contracting Parties to the Helsinki Convention should, while awaiting Guidelines approved by IMO, apply the attached Guidelines for the capacity calculation of sewage systems.



Guidelines for capacity calculation of sewage systems on board passenger ships

These Guidelines are applicable to sewage systems to be installed in passenger ships in order to meet the requirements of the Helsinki Convention.

They deal with sewage (black water) and grey water. Sewage is defined in Regulation 7 of Annex IV of the Helsinki Convention. Effluent from kitchen, pantries, laundries, galleys, baths and showers is referred to as grey water. It is only sewage which is required to be treated in accordance with the Helsinki Convention. On many ships there is a connection between sewage and grey water systems so that in the following there is also given a calculation scheme for the combined system.

The total flushing systems used on board ships are the conventional system and the vacuum system.

The capacity calculations apply to passenger ships engaged in voyages with a length of more than 24 hours. They are based on the flow rate in litre per day per person.

Litre per person per day
   Conventional systemVacuum system   
Sewage (black water) 7025   
Sewage and grey water230185
The Administrations may alter these figures when the duration of the voyage is less than 24 hours or when other systems with small flow rates are installed.