June 2026 · BWTS · 8 min read
IMO just approved the amendments that close the EBP and rewrite the compliance rules for every vessel with a ballast water management system. They enter into force in 2028. The preparation window is now.
For the past nine years, the BWM Convention has operated under an informal understanding: if your system was installed, approved, and running, an inspector would not detain you solely because the discharge did not meet D-2 biological limits. That was the Experience-Building Phase. It ends when the MEPC 84 amendments enter into force — expected spring 2028.
The amendments were approved at MEPC 84, held in London from 27 April to 1 May 2026. Adoption is scheduled for MEPC 85 in November 2026. Entry into force follows approximately 16 months after that. The corridor between now and spring 2028 is not long, and what changes matters.
What the EBP actually meant — and what ending it changes
The EBP was not a grace period in the way most people understood it. It never suspended the D-2 discharge standard. It suspended penalties for failing to meet it, under specific conditions: the system had to be correctly installed, the BWMP had to be approved, the system had to be operational, and any malfunction had to be reported to the port state before discharging.
In practice, most vessels failed to meet at least one of those conditions. The 2025 CIC found that BWMS operability — not documentation — was the leading cause of CIC-related detentions. A non-operational system is not a D-2 failure. It is a failure to meet the EBP conditions. That distinction has protected many operators who did not realise it was protecting them.
When the EBP closes, that protection goes with it. A system that fails D-2 discharge testing — regardless of whether it was “running” — will be a detainable deficiency. The instrument for measuring that is still being finalised at MEPC 85, but the direction is clear.
Key mechanism: The EBP non-penalisation condition required that the BWMS be “working properly.” Working properly means achieving D-2 discharge limits — not just powered on and generating alarms. Once the amendments enter into force, there is no longer a distinction between the two. The D-2 standard becomes the only standard.
What MEPC 84 actually changed in the Convention
The approved amendments do not introduce a new discharge standard. The D-2 limits stay as they are. What changes is the regulatory architecture around implementation, documentation, and maintenance. These are not administrative refinements. They directly affect what a PSC officer can cite.
The Ballast Water Management Plan requirements expand significantly. Under the revised G4 Guidelines, adopted through resolution MEPC.409(84), BWMPs must now include vessel-specific procedures for challenging water quality conditions — not a reference to IMO circular MEPC.387(81), but actual documented procedures for how that specific vessel handles CWQ. BWMPs must also include detailed contingency measure procedures, maintenance schedules, and must be updated whenever the BWMS is upgraded or retrofitted.
The amendments also clarify the legal basis for discharging unmanaged or partially managed ballast water in CWQ conditions or when a contingency measure is being applied. This sounds like relief, but read it carefully: the discharge is only permissible on the high seas or in areas designated by the port state. European port waters are not among those areas. And the BWMP must document the specific circumstances. If it does not, the exemption does not apply.
The BWM Certificate format was also revised. References to the D-1 standard — now phased out — are removed. The certificate must now include the type approval certificate number, the date of issuance, and the type-approving administration. An inspector looking at a vessel certificate that does not include those fields after entry into force will raise it.
What this means for BWMPs right now: The revised G4 Guidelines are already adopted. That means flag states and class societies will start aligning their BWMP approval templates to the new requirements ahead of formal entry into force. A BWMP that was approved in 2020 and has not been updated since will not meet the new standard. If the vessel has had the BWMS serviced, upgraded, or had any component replaced, a BWMP review is now mandatory — not advisory.
The BWMS Code amendments: not finished yet
The most technically significant item from MEPC 84 was not finalised. The amendments to the BWMS Code — the mandatory type approval standard — are still being worked through a Correspondence Group, with finalisation targeted for MEPC 85 in November 2026.
What is known from the meeting documents is the direction: strengthened test water conditions for land-based type approval testing, and enhanced endurance testing requirements. This matters for manufacturers. A system that holds current IMO type approval may need to requalify under the new Code. The exact threshold — which systems require retesting, which grandfathering provisions apply — will be determined at MEPC 85.
For operators with older installed systems, the relevant question is whether the type approval held by the system onboard will remain valid after the new Code enters into force alongside the Convention amendments. That question does not have a final answer yet. IMO has confirmed the intent for simultaneous entry into force of the Convention amendments and the revised BWMS Code. What this means for installed systems grandfathered under the previous Code is something flag states will need to address explicitly.
The timeline from here
| Date | Event |
|---|---|
| May 2026 | MEPC 84 — Convention amendments approved. G4 Guidelines adopted. BWMS Code amendments progressed but not finalised. |
| November 2026 | MEPC 85 — Convention amendments expected for formal adoption. BWMS Code amendments expected to be finalised. |
| Spring 2028 | Entry into force — Convention amendments and revised BWMS Code take effect simultaneously. EBP formally closes. |
| From now | Preparation window — BWMPs should be reviewed against revised G4. Systems approaching major service intervals should be assessed against the direction of BWMS Code revisions before MEPC 85 finalises the detail. |
What this means in practice
The 2025 CIC results already showed where fleets were exposed. BWMS operability was the top detention driver. BWRB completeness and crew familiarisation followed. All three of those failure modes become harder to defend after entry into force — the EBP buffer that absorbed them is gone.
The new BWMP requirements add a specific obligation that will catch vessels off guard: CWQ procedures must be vessel-specific. Port state officers can and will check whether the procedures in the BWMP actually apply to the system installed on that vessel, not whether a generic reference to IMO guidance is present. A BWMP written for the original system that has since been upgraded, or written generically without vessel-specific ballast flow data, will fail that check.
For vessels calling European ports — particularly in the Paris MOU area — this matters now, not in 2028. Class societies and flag states are already updating their BWMP approval frameworks to align with the adopted G4 Guidelines. The survey window before MEPC 85 finalises the BWMS Code amendments is the right time to identify which systems on the managed fleet may face type approval exposure.
The EBP gave the industry nine years to get systems installed and running. What it did not give was nine years to understand how the systems work. The amendments closing it assume that time has been used. For vessels where it has not, 2028 will arrive quickly.
