Ships struggle with ballast water compliance framework

The Republic of Korea contributed to the discussion with a detailed report of field testing conducted between 2019 and 2024. Its findings show BWMS operating in challenging water quality frequently fail to treat water to regulation D-2 standards, even after mitigation measures have been taken. Korean data indicated systems equipped with UV treatment or electrolysis technology routinely encountered operational limits such as UV dose or intensity failures.

Intertanko, in co-ordination with ICS and others, submitted an additional analysis showing when ships are forced to conduct extended ballast water exchange procedures due to bypass, there is a measurable rise in CO2 emissions. In a set of 48 voyages by Intertanko members, route deviation and additional treatment led to an average 9.0% increase in CO2 output and a 6.4% increase in ships’ operational Carbon Intensity Indicator (CII).

“Remedial measures… have been found to negatively impact CII, resulting in lower ratings and consequences for Statements of Compliance,” the submission noted.

Japan brought forward a proposed framework for flag state inspection and port state control that attempts to address these operational limitations more systematically. The Japanese delegation acknowledged that even properly maintained and operated BWMS may not meet D-2 standards due to more stringent water conditions at intake compared with type-approval test environments.

It stated, “Responsibility should neither be imposed on shipowners, shipyards, nor BWMS manufacturers” under these circumstances.

Oman responded to the Japanese proposal by broadly supporting the creation of a harmonised framework but warned of the risk of introducing compliance loopholes if enforcement becomes too lenient. Oman proposed that reverification processes following initial non-compliance findings must be time-bound and linked to corrective measures.

The backdrop to these discussions is a growing consensus that the BWM Convention, while robust in theory, is straining under the realities of shipboard operations.

Korea’s study demonstrated even when crews follow correct decontamination procedures – ballast water exchange followed by treatment – systems frequently fail to achieve operational thresholds due to poor intake quality.

As ICS and Intertanko noted, “There is a need for improvement in all relevant aspects ranging from BWMS design to maintenance and crew training.”

While the Convention’s review continues, the Committee has been asked to consider not only technical refinements but also greater clarity around enforcement expectations, bypass approval processes and emissions trade-offs.

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