Applicability: shipowners, ship operators, ship managers, ship masters, designers and shipbuilders. 

The International Maritime Organisation has issued new guidance relating to the Ballast Water Management Convention, as follows:

This resolution offers interim guidance on the application of the BWM Convention to ships operating in challenging water quality conditions. 

This circular provides guidance for the temporary storage of treated sewage and/or grey water in ballast water tanks. 

Challenging water quality conditions

MEPC.387(81) aims to address operational challenges encountered by a vessel fitted with a type-approved, properly installed and maintained ballast water management system (BWMS) when the ship is operating in challenging water quality (CWQ) conditions*. 

The guidance includes:

  • Recommended steps to identify when a BWMS is inoperable owing to CWQ
  • Actions to avoid bypass of the BWMS
  • Steps to recover from bypass, including actions to return to compliance with the D-2 discharge standard
  • Planning, record-keeping and communication principles.

*Challenging water quality (CWQ) refers to ambient uptake water having quality parameters (including but not limited to high total suspended solids, or turbidity) that cause a properly installed, maintained and operated type-approved BWMS to be temporarily inoperable due to an operational limitation or an inability to meet operational demand. However, temperature and salinity are not parameters that define CWQ.

Temporary storage of treated sewage and grey water

BWM.2/Circ.82 provides guidance on procedures for the temporary storage of treated sewage (TS) and/or grey water (GW) in ballast water tanks. 
​​​​​Such temporary storage should only be used as an option in specific ports and areas which restrict the discharge of TS/GW and where the ship does not have dedicated tanks with adequate storage capacity for TS/GW. 

The Ballast Water Management Plan (BWMP) of such a ship should be modified to include a ship-specific change-over procedure, from ballast water storage to TS/GW storage and back to ballast water storage, including pump and piping associated with the dual-purpose ballast water tanks, with specific details on how the flushing is conducted. The ballast water tanks to be used for temporary storage of TS/GW should be identified in the BWMP.

What should shipowners and ship operators do now?

Shipowners, ship operators, masters, and officers of ships with temporary storage of treated sewage and/or grey water in ballast water tanks, or for ships which operate in areas with challenging water quality, should properly implement these procedures.

Unless instructed otherwise by the ship’s flag Administration, to implement BWM.2/Circ.82 and CWQ requirements, procedures should be incorporated in the ship’s BWMP, as non-mandatory appendices, in a similar manner to how other contingency measures procedures are treated**. There is no need to submit the ship’s BWMP for reapproval after a modification to the “non-mandatory” section.

**See Guidelines for Ballast Water Management and Development of Ballast Water Management Plans (G4) – Part B – Guidelines for the Development of Ballast Water Management Plans – 4 Non-Mandatory Information (Resolution MEPC.127(53) as amended by resolution MEPC.306(73)).

For further information

For further information or advice, please get in touch with your local Lloyd's Register office or contact

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