Ballast water

​​The purpose of the ballast water management convention is to prevent the introduction of invasive species from ships' ballast water. 

The ballast water management convention entered into force on 8 September 2017.


The requirements for the exchange of ballast water, i.e. the so-called D-1 standard requiring ballast water exchange on open seas, has entered into force (see the guidelines).

The requirements for the treatment of ballast water, on the other hand, i.e. the so-called D-2 standard requiring the installation of a ballast water treatment system, will enter into force as follows: Existing ships due for renewal surveys during the period 8 September 2017 to 8 September 2019 are not required to have treatment systems installed until during the period 8 September 2022 to 8 September 2024, and ships of less than 400 GT must comply with the D-2 requirements by 8 September 2024, at the latest.


The concept of "Same Risk Area", developed in Denmark, has now been approved by the IMO, and it has been decided that it can be used already now. This means that, rather than making a risk assessment per ship route, you can make a risk assessment for minor sea areas (following agreement among the authorities of all the countries affected); this would be considerably easier to handle for both shipowners and the authorities.

Type approval

Ballast water treatment systems are type-approved according to IMO guidelines (G8), and ships calling at US ports are type-approved according to a USCG procedure. Ballast water treatment systems approved according to G8 by 28 October 2018 may be installed on board ships by 28 October 2020. 

The Code for approval of ballast water treatment systems (BWMS Code) must be used for type-approvals after 28 October 2018, at the latest, and systems installed on board ships must have been approved according to the code after 28 October 2020.

On-going work in the IMO – Experience Building Phase

The work future-proving the convention has been initiated, and it is expected that it will be possible to adopt a revised text – based on experience retrieval – in 2022.​​


Maritime Regulation and Legal Affairs