Maritime Regulations Guidance - Control and Management of Ballast Water


( Loading and discharging ballast water is an essential part of a ship’s operation, with large ships requiring many thousands of tonnes of water to maintain their stability, draft and manoeuvrability. By the very nature of the operation, this ballast water contains hundreds of micro and macroscopic species that will be carried to new destinations by the ship. Some of these species will not survive the journey; however, the species that do survive may establish themselves in a new environment if the biological and physical conditions are favourable. Such non-native species may cause serious ecological, economic and public health impacts, particularly when they become invasive.

In response to this, the International Maritime Organization (IMO) through its Marine Environment Protection Committee (MEPC), developed the “International Convention for the Control and Management of Ships’ Ballast Water and Sediments” which was adopted at a Diplomatic Conference during 2004.

Further background information and links to the Guidelines that have been developed to support the Convention are available from the IMO website, including a document detailing available ballast water management guidance and a list of approved ballast water treatment systems. This information can be found on the IMO website

Control and management of ships’ ballast water and sediments

The Ballast Water Management (BWM) Convention entered into force internationally on 8th September 2017. The Convention applies to all vessels that operate in the waters of more than one Party to the Convention (internationally operating vessels). The Convention applies to all vessels, regardless of size/tonnage, that are entitled to fly the Flag of a Party to the Convention.

The Convention does not apply to:

  • Ships not constructed/designed to carry ballast water;
  • Ships that only operate in the waters of a single Party to the Convention (Domestically operating vessels);
  • Ships operating in the waters of a single Party and on the High Seas;
  • Warships, naval auxiliary or ships owned or operated by a State and used only on Government non-commercial service; and
  • Permanent ballast water in sealed tanks on ships that is not subject to discharge.

The Convention defines ship as a vessel of any type whatsoever operating in the aquatic environment and includes submersibles, floating craft, floating platforms, Floating Storage Units (FSU’s) and Floating Production, Storage and Offloading vessels (FPSO’s). Floating craft encompasses a wide variety of vessels that operate in the marine environment and use ballast water for stability, heeling or operating purposes and includes, but is not limited to, fishing vessels, large yachts, dumb barges etc.

Ballast water management convention requirements

Ships subject to the Convention requirements will be obliged to conduct ballast water management in accordance with the provisions within the Convention, as outlined below.

Ballast water management plan

Ships shall carry and implement a Ballast Water Management Plan that has been approved by the Administration. The plan must include details of the safety procedures for the ship and crew and provide a detailed description of the actions to be taken to implement the ballast water management requirements. Further information is provided in IMO Guideline G4.

Ballast water record books

Ships shall carry a Ballast Water Record Book, which must be completed after each ballast water operation. The form of the Ballast Water Record Book should emulate that contained in Appendix II of the Convention.

Ballast water management standards

The Convention, as amended, introduces the phased implementation of two ballast water standards:

  • D1 – Ballast Water Exchange Standard; and
  • D2 – Ballast Water Performance Standard.

Currently, any ballast water discharged from a ship shall be required to meet either the D-1 or D-2 standard until such time as the ship is required to implement the D-2 standard. Ships currently meeting the D-2 standard (usually through the use of a ballast water treatment system), can opt to meet D-1, but it is recommended that any fitted equipment is operated. The Conventions implementation schedule means that the use of ballast water exchange, which meets the D1 standard, as a management method will be replaced by a requirement for ballast water to meet the D2 discharge performance standard (usually through the use of a ballast water treatment system).

Sediment management for ships

All ships shall remove and dispose of sediments from spaces designed to carry ballast water in accordance with the ship’s Ballast Water Management Plan.

Duties of officers and crew

Officers and crew shall be familiar with their duties with respect to the implementation of the ship’s Ballast Water Management Plan.


The requirement to meet the ballast water management standards shall not apply to:

  • the uptake and discharge of ballast water necessary for ensuring the safety of the ship in emergency situations;
  • the accidental discharge or ingress of ballast water as a result of damage to the ship or its equipment;
  • the uptake or discharge of ballast water for the purpose of avoiding or minimising pollution incidents from the ship;
  • the uptake and subsequent discharge on the high seas of the same ballast water; or
  • the discharge of ballast water from a ship at the same location where the whole of the ballast water originated, provided no mixing of unmanaged ballast water from other areas has occurred. If mixing occurs, the ballast water is subject to management in accordance with the Convention.


Exemptions to the requirement to meet the management standard may be granted in specific circumstances. Exemptions may only be granted to a ship or ships on a voyage(s) between specified locations, ships which operate within a defined area or to a ship that operates exclusively between specified locations. An exemption can be effective for no longer than 5 years. The exemption can only be granted if ballast water is not mixed, other than in the locations specified on the exemption, and must be based on a detailed risk assessment taking into consideration the IMO Guidelines (Guideline G7).

Equivalent compliance

Vessels used solely for recreation or competition or crafts used primarily for search and rescue, that are less than 50m in overall length and have a maximum ballast capacity of 8m3 may apply to their Administration for equivalent compliance. The decision to grant equivalent compliance will be determined based on the guidance developed by the IMO, Guidelines for ballast water management equivalent compliance (G3). There is no other equivalent compliance available under the Convention. Any alternative methods of meeting the discharge requirements of the Convention are known as ‘Other Methods’.

Survey and certification of ships

Ships of 400 gross tonnage and above shall be subject to a survey and certification regime as stipulated within the Convention. Vessels under this threshold are still required to meet the requirements of the Convention. Administrations are required to establish appropriate measures to ensure compliance by vessels of less than 400gt.

Ballast water management standards

The Convention requires that ballast water is managed to meet the standards set and allows for the phased introduction of two standards as detailed under Regulations D1 and D2. D1 details requirements relating to ballast water exchange and D2 details allowable limits for organisms within the ballast water discharge. The Convention allows for D1 to be used until such time as D2 is required but does not prevent ships operating to the D2 standard ahead of schedule.

D1 - Ballast water exchange (BWE)

The standard set by the Convention states that ships undertaking BWE shall do so with an efficiency of at least 95% volumetric exchange of ballast water. For ships exchanging the ballast water by the pumping-through method, pumping through three times the volume of each ballast tank will be considered equivalent to meeting the 95% standard.

Ships undertaking ballast water exchange should conduct the operation at least 200 nautical miles from the nearest land and in water at least 200 meters deep; or in cases where the ship is unable to conduct ballast water exchange in accordance with the above, as far from the nearest land as possible, and in all cases at least 50 nautical miles from the nearest land and in water at least 200 meters deep.

In sea areas where the minimum distance and depth criteria cannot be met, the Parties to the Convention have the ability, within their waters, to designate BWE areas. Areas designated by a Party should be used in compliance with the terms of use stipulated by the Administration(s) responsible for the designation. Vessels may be required to deviate or delay their voyage in order to use the designated BWE area.

Owners are urged to contact relevant port State Administrations for confirmation of BWE requirements within local waters.

D2 - Ballast water performance standard

D2 stipulates the acceptable level of organisms that may be found within discharged ballast water. The D2 Standard specifies that treated and discharged ballast water must have:

  • fewer than ten viable organisms greater than or equal to 50 micrometers in minimum dimension per cubic metre;
  • fewer than ten viable organisms less than 50 micrometres in minimum dimension and greater than or equal to 10 micrometers in minimum dimension per millilitre.

In addition, a ballast water discharge of indicator microbes, as a health standard, shall not exceed the following specified concentrations:

  • Toxicogenic Vibrio cholerae (O1 and O139) with less than one colony-forming unit (cfu) per 100 millilitres or less than 1 cfu per 1 gram (wet weight) zooplankton samples;
  • Escherichia coli less than 250 cfu per 100 millilitres;
  • Intestinal Enterococci less than 100 cfu per 100 millilitres

Ballast water treatment equipment is developed, and type approved on the basis of the equipment’s ability to treat the ballast water to the required standard. Although not the only way to meet the D2 standard, the installation of an appropriately type approved ballast water treatment system will be the most common method used.

Other methods of ballast water management

Other methods may be accepted as alternatives to either D1 or D2 provided the methods ensure at least the same level of protection to the environment, human health, property or resources and are approved in principle by the IMO.

Ballast water management implementation schedule

The requirement to meet either D1 or D2 standards does not apply to ships that discharge ballast water to a reception facility that has been designed taking into consideration Guideline G5: Guidelines for ballast water reception facilities. Ships will be required to meet either the D1 or D2 standard until such time as required to meet D2. The table below outlines the implementation dates for the D2 standard.

BWM Convention D2 Implementation Schedule Table.

Ballast water management requirements in specific areas

In addition to the IMO’s Ballast Water Management Convention, specific areas of the oceans have additional requirements for ballast water control, which you must adhere to.

United States of America

Ships trading in the US should be aware that ballast water management requirements within US waters differ from that outlined in the BWM Convention. Operators are advised to contact the relevant authority for further information.

Antarctic waters

There are specific requirements for the uptake or discharge of ballast water in Arctic or Antarctic waters. You must follow these unless the safety of the ship is jeopardised by a ballast exchange, or where it is necessary for saving life at sea.

A ballast water management plan is to be prepared for vessels entering Antarctic waters, taking into account problems of ballast water exchange in Antarctic conditions. Your vessels should keep a record of ballast water operations.

Ballast water should first be exchanged before arrival in Antarctic waters or at least 50 nautical miles from the nearest land in waters at least 200 metres deep. Similarly, ballast water taken on in Antarctic waters should be exchanged north of the Antarctic Polar Frontal Zone, and at least 200 nautical miles from the nearest land in water at least 200 metres deep.

The release of sediments during the cleaning of ballast tanks should not take place in Antarctic waters. Vessels that have spent significant time in the Arctic should discharge and clean tanks before entering Antarctic waters. If this is not possible, sediment accumulation in ballast tanks should be monitored and sediment disposed of in accordance with the ship’s ballast water management plan.


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