Ballast Water Management

The environmental problem of invasive species

Module objectiveUnderstand how ballast water and sediments transfer organisms between ecosystems and distinguish transfer prevention, D-1 exchange and D-2 performance.

Ships that take on ballast water for stability in one port and discharge it in another carry, along with the water, aquatic organisms, larvae and sediments that can survive the voyage and establish themselves in an entirely foreign ecosystem, with sometimes serious ecological and economic consequences.

The pathway by which invasive species are introduced, two introduction examples and the Convention’s two answers.

Hull and niche-area biofouling is a separate vector. Ballast management reduces organism and pathogen transfer; it neither guarantees sterile water nor replaces biofouling management. Risk depends on organisms, quantity, survival and receiving-site conditions.

The Ballast Water Management Convention

Module objectiveDetermine whether the Convention, survey/certification regime and principal B-1–B-6 and E-1 requirements apply to an individual ship.

The BWM Convention was adopted on 13 February 2004 and entered into force on 8 September 2017. It is an IMO instrument distinct from MARPOL.

Application and certification

The Convention applies to ships entitled to fly the flag of a Party and ships operating under the authority of a Party, subject to Article 3 exclusions and determinations. Warships, naval auxiliaries and State ships used only on government non-commercial service are excluded; limited trades require verification of the competent Party’s decision.

Section E survey and certification generally applies to ships of 400 GT and above, excluding floating platforms, FSUs and FPSOs. For other ships subject to the Convention, the Party establishes appropriate measures. Flag, operating area, service, tonnage, exclusions, exemptions and implementing law must be checked.

BWM Convention milestones distinguishing requirements in force, adopted guidance and approved draft amendments.

Main obligations

• B-1: approved ship-specific BWMP.
• B-2: traceable BWRB retained for the required periods.
• B-3/B-4: applicable standard and exchange conditions.
• B-5/B-6: sediments, duties and familiarisation.
• E-1: survey and certification where applicable.

The 400 GT threshold is not a general exemption from substantive duties. Article 3 also excludes, on its terms, ships not designed to carry ballast and permanent ballast in sealed tanks that is not discharged. Retain the documentary basis for a ship’s exclusion or exemption; do not infer it solely from tonnage or a domestic voyage.

The D-1 and D-2 standards

Module objectiveApply D-1/B-4 criteria and interpret all five D-2 limits without confusing the general timetable with exceptions and contingency measures.

D-1 defines volumetric exchange; D-2 sets biological discharge performance. The general D-2 timetable was completed in 2024, subject to specific grounds for exclusions, exemptions and other permitted arrangements.

D-1: what «exchange» actually means

The D-1 standard is met with an effective volumetric exchange of at least 95%. Using the pumping-through method the criterion is taken as met by pumping three times the volume of each tank; less than three times is acceptable only where 95% is demonstrated.

Regulation B-4 sets out where: at least 200 nautical miles from the nearest land and in water at least 200 metres deep. Where that is not possible, as far from the nearest land as possible and in all cases at least 50 nautical miles away and in water at least 200 metres deep. Where neither is achievable, the port State may designate exchange areas in consultation with neighbouring States. And there is a clause worth knowing: the ship is not required to deviate from its route or delay the voyage in order to exchange.

The D-1 criterion with the Regulation B-4 distances, and the five numerical limits of D-2.

D-2 in figures

This is the heart of the subject, and what the course must be able to state without hesitating: D-2 is not «clean water», it is a set of five measurable limits.

Indicator microbes also address public-health risk: meeting the larger-organism limits does not automatically demonstrate microbiological compliance.

D-2 is a discharge performance standard, normally achieved through an approved BWMS, not a technology name. Size classes refer to an organism’s minimum dimension and numerical limits are strictly less than, not “less than or equal to”. Exchange can remove organisms with the water but guarantees neither elimination nor D-2 compliance. If exchange compromises safety, stability or strength, the master applies B-4.4 and records the reasons under B-4.5; this does not automatically authorise discharge at the next port.

How a BWMS works

Module objectiveConnect technology, type approval, system design limitations, monitoring and maintenance to D-2 performance of the individual installation.

Ballast Water Management Systems (BWMS) use combinations of physical and chemical technologies to reduce the concentration of viable organisms below the thresholds required by the D-2 standard.

Type approval no longer follows G8

The BWMS Code, MEPC.300(72), was made mandatory by MEPC.296(72), in force from 13 October 2019. Distinguish this date from the 28 October 2020 installation criterion. Check the certificate, conditions and approval limitations of the actual configuration.

A system using an Active Substance — electrochlorination, chlorination, ozone — additionally requires approval under Procedure G9, which assesses the risk to the environment, to human health and to the ship, and sets the limits for residuals at discharge.

The treatment chain, the four functions with their failure modes, and the two steps of approval.

Before each operation check certified limits: flow, salinity, temperature, UV transmittance where relevant, dose and minimum holding time. Filtration, uptake/discharge treatment and neutralisation follow the approved manual; these are not interchangeable stages. Calibrate sensors and retain alarms and records. The BWMS Code applies to systems installed from 28 October 2020 under the applicable definition; earlier systems require verification of their approval and acceptance conditions, not an automatic declaration of invalidity.

When the system cannot treat

Module objectiveDistinguish commissioning, technical malfunction, challenging water quality, A-3 exceptions and contingency measures agreed with the port State.

An approved BWMS must be verified on its individual installation and managed under the approved plan. Technical failure, challenging water quality, A-3 exceptions and contingency are different categories.

Commissioning test

The regulation E-1 commissioning test at initial survey and at an additional survey undertaken to install a BWMS demonstrates that mechanical, physical, chemical and biological processes work correctly. BWM.2/Circ.70/Rev.1 calls for a representative discharge sample, analysis of at least the two D-2 size classes, assessment of self-monitoring and collection/analysis independent of the maker or supplier to the Administration’s satisfaction. It is not a full repetition of type approval.

A failed result creates a technical non-conformity to diagnose and rectify before certification. Cost and responsibility among owner, yard, installer, maker and testing provider depend on cause, contract and evidence.

A-3 exceptions, challenging water quality and contingency are distinct paths requiring records and authority agreement where applicable.

Regulation A-3: defined exceptions

A-3 identifies limited cases: ship safety or saving life; accidental discharge or ingress resulting from damage subject to its conditions; avoiding or minimising a pollution incident; uptake and discharge on the high seas of the same water; and uptake and discharge at the same location without relevant mixing. It is not a general container for BWMS failures.

Contingency: case-by-case with the port State

For non-compliant water, ship and port State communicate and consider BWM.2/Circ.62 options: BWMP actions; discharge to another ship or suitable facility; a method acceptable to the port State; D-1 exchange under the approved plan; revised schedule, internal transfer or retention on board. Discharge remains subject to authority acceptance and conditions. Failure, repair plan, consultation and decisions must be recorded.

Challenging water quality

The reference is MEPC.387(81). It addresses ambient characteristics such as high suspended solids or turbidity that prevent the BWMS from meeting operational demand; it does not automatically cover temperature or salinity outside system design limitations or replace technical-failure contingency. Procedures must be ship-specific and included in the BWMP.

Mandatory commissioning from 1 June 2022 concerns installation verification under E-1: an additional survey confirms the test when undertaken to install a BWMS. Not every significant repair automatically requires new biological commissioning; establish the required verification with the Administration. Commissioning analysis is indicative under MEPC.325(75), using BWM.2/Circ.70/Rev.1 criteria. In CWQ, treat as much as practicable and regard bypass only as a last resort under the plan. Following bypass, plan tank and line decontamination and compliance of subsequent discharge: exchange plus treatment alone may be insufficient. Record volumes, tanks, conditions, attempts, communications and decisions.

Required documentation

Module objectiveVerify consistency, validity, approval and traceability of the BWMP, BWRB, certificate and electronic records.

Documentation management is central to demonstrating compliance with the Convention, both in routine inspections and in targeted PSC checks.

The Record Book changed form on 1 February 2025

Resolution MEPC.369(80) replaced the model Ballast Water Record Book. From 1 February 2025 entries follow a standardised format with operation codes from letter A to H and item numbers, on the model of the Oil Record Book; the guidance for completing it is BWM.2/Circ.80/Rev.1, which also contains examples for the unusual cases. The requirement applies to existing ships as well, not only to new buildings.

Retention is set by Regulation B-2: two years on board from the last entry, then three years under the company's control. Each operation is recorded without delay and signed by the officer in charge; each completed page is signed by the master.

From 1 October 2025, amendments MEPC.383(81) recognise an electronic BWRB. Where it replaces the paper book, the system must be approved by the Administration taking account of MEPC.372(80) and preserve authentication, amendment traceability, master verification and availability for inspection. The 2026 G4 is adopted guidance under MEPC.409(84); Convention drafts approved at MEPC 84 are not yet in force.

The international BWM certificate records statutory verification; the type approval certificate concerns the BWMS model. They are not interchangeable and alone do not guarantee every discharge is compliant. Keep the approved BWMP, certified method, actual installation and limitations consistent. Entries must distinguish uptake, management, discharge, reception-facility transfer, exceptional operations, failures and cleaning; also retain alarm and maintenance evidence. An electronic record book needs the Administration’s declaration and must remain accessible and verifiable during inspection under the applicable regime.

Additional requirements in certain areas

Module objectiveIdentify C-1 measures, C-2 warnings and A-4 exemptions applicable to a ship’s route, ports and ballast water.

The BWM Convention does not use MARPOL’s “special areas” category. Section C governs additional measures and warnings; regulation A-4 governs limited exemptions.

C-1 measures and C-2 warnings

C-1 measures are normally notified at least six months in advance, but the Convention provides for emergencies and epidemics. Voyage preparation should consult IMO, coastal and port authority communications, notices to mariners and agent instructions, recording source, date and applicability. C-2 uptake warnings belong in voyage planning before the operation.

A-4 exemptions

An exemption covers voyages between specified ports or locations, lasts no more than five years with intermediate review, is based on a G7 risk assessment, and must not impair the environment, health, property or resources of adjacent or other States. Potentially affected States should be consulted. Route, ports, validity, conditions, mixing and records must be checked before use.

The six-month C-1 notice has Convention exceptions for emergencies and epidemics. For A-4 verify no mixing with water or sediments from ports outside the exemption and record the exemption in the BWRB. Permission limited to one route does not automatically extend to a new port.

The United States framework: USCG type approval and EPA discharge standards

Module objectiveSeparate USCG type approval, federal operational requirements, EPA/VIDA standards and State or local requirements for a ship trading to the United States.

The United States is not a Party to the BWM Convention. Subject vessels operate under 33 CFR Part 151 and BWMS type approval under 46 CFR Part 162.060. IMO approval does not automatically equal USCG type approval: the US certificate, operational limitations and installation must be checked.

USCG type approval and testing methods

The historical distinction between “living” and “viable/capable of reproduction” remains relevant but should not be frozen at 2022. Policy Letter 02-22 defines an evaluation process, while USCG separately publishes testing methods and protocols accepted under VIDA. Current status must be checked before technical decisions; it is wrong to say UV systems generally lack US approval.

The US framework separates USCG type approval, EPA discharge standards and the actual status of the VIDA transition.

EPA discharge standards and VIDA transition

EPA published the Vessel Incidental Discharge National Standards of Performance on 9 October 2024. USCG implementation, compliance and enforcement regulations are to follow. Until those rules are final, effective and enforceable, the 2013 VGP, current USCG rules and applicable State and local requirements continue. 9 October 2026 is the statutory deadline assigned to USCG, not an automatic switch.

AMS is a transitional solution tied to the compliance date and approval of the individual ship and system; status must be checked from the actual documents.

Position at 15 September 2026: the 27 August 2026 Federal Register records withdrawal of the Notice of Intent for a programmatic environmental review of certain viability-testing methods because available information was insufficient. This neither generally approves methods nor automatically revokes existing BWMS certificates. Policy Letter 02-22 remains the process for potential future submissions. Check the USCG certificate, operating limits, AMS conditions and reporting/discharge duties separately. AMS permits temporary use within the allowed period relative to the ship’s compliance date; assume neither universal expiry nor unlimited validity. The EPA VIDA page confirms that transition requires final, effective and enforceable USCG rules.

PSC inspections on ballast water

Module objectivePrepare operational evidence for the four PSC stages and interpret the 2025 CIC data with correct source attribution.

Guidelines MEPC.252(67) describe four graduated stages: initial inspection; more detailed inspection where clear grounds exist; sampling with indicative analysis; and detailed analysis where needed. An indicative result is not by itself a final determination of non-compliance.

The four PSC stages and official preliminary results of the 2025 BWM CIC.

Recurring controls

• Certificate, BWMP and BWRB consistent with ship, voyage and system.
• Operation, alarms, self-monitoring, maintenance records and commissioning.
• Actual crew knowledge of ship-specific procedures.
• Sampling, timing and action under the Guidelines and authority procedures, avoiding undue delay.

2025 BWM CIC: official preliminary data

The critical area identified was BWMS operation and maintenance (code 14811, question 6). The data do not support undocumented regional rankings or further claims.

The 184 all-cause detentions concern inspections with a CIC questionnaire (184/6,930 = 2.66%); the 30 directly related to BWM represent 0.43% of that same denominator. Do not use 9,244 as denominator for these percentages. These figures are from the Tokyo MoU preliminary release of 17 March 2026, not a global total or a Tokyo/Paris sum.

Sediment management

Module objectiveApply regulation B-5 and G12 to prevention of accumulation, safe removal, recording and disposal of sediments.

Regulation B-5 requires sediments from spaces designated to carry ballast water to be removed and disposed of in accordance with the BWMP.

Design, removal and disposal

Ships constructed from 2009 to which the provision applies should, as far as practicable, minimise uptake and accumulation, facilitate removal and provide safe access, taking G12 into account.

Location and method depend on the approved plan, available reception facilities, safety procedures and applicable State or port rules. Regulation B-5 does not contain a universal geographical prohibition for every sediment and circumstance.

Entry into ballast tanks is enclosed-space work: apply risk assessment, isolation, permit, ventilation, atmosphere testing and rescue readiness under the SMS and applicable rules. Do not enter to remove sediments without these conditions. Agree reception, quantity and transfer arrangements with the facility and retain its receipt and records.

Crew training

Module objectiveDefine ship-specific familiarisation enabling crew to operate, recognise deviations, respond and record correctly.

As with the other management systems seen in previous courses, genuine compliance with the Convention depends on the crew's competence in correctly operating the system and completing the required documentation.

Elements of good training

• Understanding of the basic operation of the BWMS installed on board, not just start/stop procedures.
• Recognition of malfunction signals and immediate intervention procedures.
• Correct completion of the Record Book in real time, not after the fact.

B-6 requires familiarity with assigned duties and the ship-specific plan; it does not itself create a separate universal BWM certificate. Verify practical competence in system limits, alarms, deviations and records through demonstrations and scenarios. Document initial familiarisation, personnel or system changes and updates; use a language understood by those involved.

Integrating BWM into the SMS, maintenance and voyage planning

Module objectiveIntegrate BWM with the SMS, planned maintenance, stability, voyage/cargo planning and energy management without conflating their legal bases.

The BWM Convention remains distinct from MARPOL, ISM, stability requirements and climate regimes. On board, however, their processes share people, machinery, data and decisions. The BWMP should interface with the SMS, planned maintenance, familiarisation, risk assessment, passage/voyage planning, cargo plan and emergency management.

Before, during and after the operation

Before: verify ballast quantities and sequence, stability and strength, BWMS flow and system design limitations, expected water quality, local restrictions, available time and contingency plan. During and after: monitor parameters, alarms, bypass, neutralisation, consumables, energy, samples and records; open defects/non-conformities and corrective action where needed.

BWMS electrical load may affect fuel and emissions, but this does not alter D-2 or turn BWM into a CII measure. Safety, biological compliance and energy performance remain distinct while their interactions are made visible.

Operational example: if turbid water reduces flow, reassess ballast time, cargo operations, stability and the port window together. Record the issue, consult the maker and authorities involved and apply the BWMP. Do not disable alarms or open bypass merely to meet the commercial schedule.

The review of the Convention: from MEPC 84 to MEPC 85

Module objectiveDistinguish instruments adopted at MEPC 84 from draft amendments expected at MEPC 85 and plan monitoring of entry into force.

MEPC 84 approved draft Convention amendments for expected adoption at MEPC 85; it did not make them mandatory. It adopted the 2026 G4 Guidelines through MEPC.409(84), inviting early application.

The review separates adopted 2026 G4 guidance from approved Convention drafts not yet in force.

Work on the BWMS Code continues intersessionally. If adopted and brought into force, the package will shift evidence towards documented maintenance, familiarisation and periodic verification.

Status checked at 15 September 2026. Adoption of MEPC.409(84) does not bring the Convention amendments into force. The resolution invites early application of the new G4 and links revocation of the previous G4 to entry into force of the amendments. Agree plan updates with the flag. New periodic tests described in the draft are not presented here as Convention requirements already in force.

Building effective BWM management

Module objectiveTranslate BWM obligations into fleet controls, responsibilities, evidence, escalation and continual improvement.

Effective management of BWM compliance requires the integration of equipment maintenance, documentary discipline and crew training, following the same principles already seen for the ISM Code and maintenance management.

Critical success factors

• Scheduled maintenance of the BWMS, with the same discipline seen in the Reliability Management course.
• Ongoing crew training, not limited to initial training alone.
• Rigorous discipline in completing the Record Book in real time.
• Monitoring of specific local requirements for the routes the ship usually serves.

For each anomaly assign an owner, action, deadline and closure evidence. Review recurring failures, CWQ operations, bypass, consumables, repair times and record discrepancies. Closure requires effectiveness verification, not merely a purchase order or spare-part receipt.