Ballast Water Management: Understanding the retrofitting of BWM Systems from 2026, 16th Edition, Volumes 1–2

Since 8th September 2024, all ships to which the BWM Convention applies, have had to comply with the Convention's ballast water discharge standard (D–2). For most ships, this has involved installing and operating a BWMS on board. This comprehensive, two-volume publication provides up-to-date guidance on BWM regulations, operations (including Port State Control (PSC) requirements) and equipment options. It is a valuable, single-point source of information for ship owners and operators.

In Volume 1, the publication looks in detail at the various treatment systems and technologies, significant components and the implications for onboard operation, maintenance and contingency measures. With the end of the installation window for fitting a BWMS to existing ships, there is a shift from retrofitting to installing on newbuilds and fulfilling maintenance contracts. However, retrofit experience remains an important consideration as there will also be a growing market for fully or partly replacing older (legacy) BWMS or systems that are not operating properly.

Now the BWM Convention has been fully in force for a year, there is an increase in PSC BWM inspection activity leading up to the end of the experience building phase (EBP) for the Convention in Autumn 2026. These PSC inspections aim to facilitate compliance by identifying deficiencies early and ensuring that ships are meeting the mandatory requirements of the Convention. There is particular emphasis on the D–2 performance standard, the provision of correct and accurate documentation for inspection and support for crew operating the systems on board.

Volume 2 provides an extensive set of data sheets on BWMS that have been type approved through the BWM Convention testing procedures. These summarise the treatment technology, type approval certification and system design limitations (SDL), so that ship owners can evaluate different systems and make an informed decision before purchasing. It is particularly important to know the SDL of a BWMS since these are the conditions and parameters under which the system is approved to operate.

The Appendices contain an updated list of IMO Guidance Documents for the BWM Convention (updated to MEPC 83). They also describe key invasive species and illustrate native and invasive geographic ranges

Foreword

The discharge of untreated ballast water (BW) has been a key factor in the transfer of non-indigenous aquatic species that have subsequently established and become pests in various parts of the world. The economic and environmental damage these invasive species can cause has been well documented and the importance of managing untreated BW on board ships cannot be overstated.

National and international requirements to control the spread of non-indigenous aquatic species through the management of BW by ballast water exchange (BWE) have been in effect in most regions and ports for many years. The International Convention for the Control and Management of Ships' Ballast Water and Sediments (BWM Convention) entered into force on 8th September 2017. As of June 2025, there were 97 contracting States to the BWM Convention, representing approximately 93.64% of the world's merchant shipping tonnage.

The BWM Convention has been fully in effect for six years. Between 8th September 2019 and 8th September 2024, all existing ships to which it applies must become compliant with the D–2 standard by the ship's next International Oil Pollution Prevention (IOPP) Certificate renewal date. The grace-period of the experience-building phase (EBP), to prevent penalisation for the discharge of non-compliant BW, will continue until September 2026. However, penalties can still be issued for failures in other areas of BWM and Port State Control (PSC) are increasing inspections to promote consistent implementation of the Convention requirements.

The IMO has made several amendments to BW requirements and guidance that have improved the testing of BWMS operations and clarity for ship owners. For example, the revised 2016 G8/BWMS Code testing regime is more rigorous and thoroughly tests the BWMS for efficacy before awarding Type Approval. The Type Approval Certificates now list the system design limitations (SDLs) of each approved BWMS so that ship owners are able to make a more informed decision before purchasing. Also, prior to an International Ballast Water Management Certificate (IBWMC) being issued, it is now mandatory to carry out biological sampling during the initial survey after installation, as part of the BWMS commissioning tests. This will provide additional reassurance of the proper operational capabilities of an installed BWMS.

The IMO interim guidance on how to ballast in challenging water quality (CWQ) conditions is especially useful to a ship's crew when a BWMS fails. It emphasises the importance that clear and practical assistance for crews must be included in the ballast water management plan (BWMP).

Going forward from the end of the Convention implementation period (September 2024) the emphasis will be on new build installations, replacement retrofits and fulfilling maintenance/servicing agreements. BWMS suppliers will have to retain the expertise to retrofit BWMS. As the pressure for ships' regulatory compliance increases, the replacement of existing/legacy BWMS with more efficient, suitable and reliable systems will be an important part of business. For a ship owner/operator, choosing a system supplier that is able to provide comprehensive and reliable servicing to a BWMS that has been retrofitted, or installed on board a new build, is a very important consideration now.

The United States is not party to the BWM Convention and its ballast water regulations can be found in the Witherbys' publication 'US Ballast Water Management Regulations', available from witherbys.com.

Volume 1 – Guidance

Foreword
Abbreviations

Part One – Introduction and Regulations
Chapter One – Introduction
1.1 Ballast Water
1.2 Sediment
1.3 Aquatic Species
1.4 Ballast Tank Configuration
1.5 Biofouling
Chapter Two – IMO Regulations
2.1 Application of the BWM Convention
2.2 The IMO Approval Process
2.3 Same Risk Area (SRA) Concept (the Management of Risk)
2.4 Temporary Storage of Grey Water/Treated Sewage in Ballast Tanks
2.5 The Schedule for Compliance
2.6 Transparency and Effectiveness of G8 Type Approval
2.7 Port State Control (PSC) Procedures for Sampling and Analysis
2.8 Ballast Water Management Manual – How to do it
Chapter Three – Local and Regional Regulations
3.1 Americas
3.2 United Kingdom
3.3 Polar Waters
Chapter Four – Alternatives to Using a BWMS On Board
4.1 Port Reception Facilities
4.2 Contingency Measures
4.3 Port-based Ballast Water Treatment
4.4 Sediment Control
Part Two – Implementation of Regulations
Chapter Five – Port State Authorities and Port State Control
5.1 Port State Requirements
5.2 Existing Conditions
5.3 Notification
5.4 Inspection, Monitoring and Enforcement
Chapter Six – The Financial Implications of BWM Legislation
6.1 Cost of Compliance with BWM Legislation
6.2 Cost of Ballast Water Management Systems (BWMS)
6.3 Issues and Costs for BWMS Manufacturers
6.4 Cost of Ballast Water Exchange (BWE)
Part Three – Treatment Systems and Operation
Chapter Seven – Introduction to Treatment Technologies
7.1 Ballast Water Management System (BWMS) Requirements
7.2 The Evolution of BWMS
Chapter Eight – Physical Separation, Thermal, Ultraviolet and Plasma Technologies
8.1 Physical Separation
8.2 Heat Treatment Technology
8.3 Ultraviolet Radiation/Advanced Oxidation Technology
8.4 Plasma Technology
Chapter Nine – Deoxygenation, Magnetic and Ultrasonic/Cavitation Technologies
9.1 Deoxygenation/Supersaturation Technology
9.2 Magnetic/Electric Field Technology
9.3 Ultrasonic and Hydrodynamic Cavitation Technology
Chapter Ten – Chemical, Biocide and Electrochemical Technologies
10.1 Chemical and Biocide Technology
10.2 Electrochemical Technology
Part Four – Practical Installation and Retrofitting Considerations
Chapter Eleven – Choosing a BWMS
11.1 Making the Decision
Chapter Twelve – The Design Stage (Feasibility Study and 3D Scan)
12.1 Retrofit Planning
12.2 Retrofitting – Feasibility Study
12.3 The 3D Scan
12.4 The Design Engineering Stage
12.5 The Role of Class
12.6 Selection of Retrofit Location
Chapter Thirteen – The Installation Process
13.1 Simplified Overview
13.2 Detailed Overview
13.3 Before Entering the Retrofit Facility
13.4 During the Stay in the Retrofit Facility
13.5 Departing the Retrofit Facility
13.6 Technical Installation and Retrofit Facility/Dry Dock Challenges
Chapter Fourteen – Commissioning of the BWMS
14.1 Delays in the Commissioning Process
14.2 IMO Commissioning Guidance
Part Five – Operations
Chapter Fifteen – Ship Administration of BWM
15.1 The Ballast Water Management Plan (BWMP)
15.2 Duties of the Ballast Water Management Officer
15.3 Ballast Water Record Book (BWRB)
15.4 Surveys
15.5 Certification
15.6 Ballast Water Reporting
15.7 Training
Chapter Sixteen – Ballast Water Sampling/Monitoring
16.1 Monitoring of Operations
16.2 Arrival Ballast Conditions
16.3 Monitoring Levels
16.4 Post-treatment Monitoring
16.5 Sampling
16.6 Sediment
16.7 Test Methods
16.8 Ballast Tank Entry
Chapter Seventeen – Maintenance and Operational Issues
17.1 Maintenance Issues
17.2 Operational Issues
17.3 Emergency/Contingency Measures
Chapter Eighteen – Preparing for Inspections
18.1 Overview of PSC Inspections
18.2 Checklist for Preparing for Inspections
18.3 Reducing Overall Risk
18.4 Ship Inspection Report Programme (SIRE) and other Inspection Regimes
Chapter Nineteen – Challenging Water Quality (CWQ)
19.1 Regulatory Guidance
19.2 Operations
19.3 Assessing BWMS Operations
19.4 Troubleshooting and Mitigation
19.5 Alternatives to Bypass
19.6 Bypass Procedure
19.7 Decontamination
19.8 Records and Roles
Chapter Twenty – Ballast Water Exchange (BWE)
20.1 BWE Operational Considerations
20.2 Sequential BWE Method
20.3 Flow-through BWE Method
20.4 BWE Operations Checklists
Appendices
A1 Key Invasive Species
A2 IMO Guidance Documents for the BWM Convention

Volume 2 – BWM Systems

Abbreviations
Chapter One – BW Systems with No Active Substances (G8)
BW Systems with No Active Substances Type Approved under the BWMS Code
1.1 Wärtsilä Aquarius UV BWMS
1.2 ARA BWMS
1.3 BAWAT BWMS Mk2
1.4 BIO-SEA – BWTS
1.5 Blue Ocean Shield (BOS) BWMS
1.6 BSKY – BWMS
1.7 CompactClean BWMS
1.8 Cyeco BWMS
1.9 Evac Evolution BWMS
1.10 GloEn-Patrol – 2.0 BWMS
1.11 KBAL – BWMS
1.12 LanghBW BWMS
1.13 Miura HK BWMS
1.14 NiBallast – BWMS
1.15 NGT BWMS (previously MMC BWMS)
1.16 Optimarin Ballast System (OBS)
1.17 PACT MARINE – BWMS
1.18 PureBallast 3.2 BWMS
1.19 Purestream – BWMS
1.20 Seascape – BWMS
1.21 Seatrium Eco LUV BWMS
1.22 SKF BlueSonic BWMS
Chapter Two – BW Systems using Active Substances (G9)
BW Systems using Active Substances Type Approved under the BWMS Code
2.1 Wärtsilä Aquarius – EC BWMS
2.2 AquaStar – BWMS
2.3 ATPS-BLUEsys BWMS
2.4 BalClor – BWMS
2.5 BALPURE – BWMS
2.6 NK-O3 BlueBallast II Plus BWMS
2.7 CleanBallast – Ocean Barrier System (CB-OBS) BWMS
2.8 Ecochlor – BWMS
2.9 EcoGuardian – BWMS
2.10 ECS-HYCHLOR – BWMS
2.11 Electro-Cleen – System (ECS)
2.12 ERMA FIRST FIT BWTS
2.13 HiBallast NF – BWMS
2.14 InTank – BWTS
2.15 JFE BallastAce – BWMS
2.16 MICROFADE II BWMS
2.17 OceanGuard – BWMS
2.18 Oceansaver– BWTS MKIIB
2.19 oneTANK BWMS
2.20 PURIMAR – BWMS
2.21 RADClean – BWMS
2.22 SeaCURE – BWMS
2.23 Senza TG2 BWMS (previously known as KURITA BWMS)
Chapter Three – Approval Status of Systems
3.1 The BWM Convention

Dr Captain Nadeem Anwar

Master Mariner, FNI, SFHEA, ACII, DoS, PGCEL, MSc (Maritime Operations), BSc (Quality Management), CertEd.

Having completed pre-sea training in 1983, Captain Anwar sailed on a variety of ship types, including VLCCs, OBOs, O/Os, gas and chemical tankers. His time at sea was mainly spent in deep-sea trade, which gave him a wide-ranging experience of navigating in different areas of the world. He left sea while in command in 1998.

In education since 1998, he is now Senior Lecturer in the Petrochemical section at Warsash Academy and Leader for MSc Shipping Operations (online).