Ballast water management (BWM) and biofouling

BWMS installations and retrofit

Compliance with regulations regarding ballast water management (BWM) will be one of the biggest challenges for the shipping industry in the near future. Eventually, all relevant vessels shall have installed a ballast water treatment system (BWTS) to inactivate invasive species and prevent the spread of non-native aquatic species in lakes, rivers and coastal waters. The IMO implementation schedule for BWTS requires the ship to install a type approved system no later than the “first IOPP renewal survey after the entry into force of the convention” if:

  1. this survey is completed on or after 8 September 2019, or
  2. a renewal IOPP survey is completed on or after 8 September 2014 but prior to 8 September 2017.

The ship should be D-2 compliant on the second IOPP renewal survey following entry into force, if the first renewal survey following the date of entry into force of the convention is completed prior to 8 September 2019 and if condition 2 above is not met.

In order to facilitate the retrofit installations of BWMS, DNV has developed a guide for retrofit installations of BWMS. The guide includes guidance on all the documents which need to be prepared and are required to be submitted for approval when a BWMS is to be installed on board a ship classified by DNV. The document approval will be followed by an initial survey of the BWMS installation and certification. The rules applicable for BWMS installations can be found online in DNV Rules for SHIP Pt. 6 Ch.7 Sec.1. The rules have to be followed to ensure safe installation and operation of the BWMS, but the rules shall also be followed to be in compliance with the BWM Convention. The current rules also incorporate the Unified Requirements for Installations of BWMS published by IACS (M74). 

DNV has gained substantial knowledge about treatment system technologies through the type approval of BWTS for IMO and USCG, and we utilize this knowledge during installation and retrofit projects.

A retrofit approval process is started by clicking “Request Alteration Approval” in Veracity. Filling out a questionnaire to identify the detailed scope of each project will be requested and an order and project folder will be set up for the alteration project.

Once the retrofit process has started, we will assign a project manager for the document approval to ensure a good communication line throughout the project. Approval engineers in all relevant disciplines will be involved in the evaluation of the installation. Normally, the following disciplines are involved during a retrofit project: environmental, piping, electrical and control systems. Updated drawings may also be required for fire safety and stability, and structure if this is modified.  

The DNV Ballast water management plan Generator may be used to produce a vessel-specific plan with user input which, combined with data from the DNV vessel database and our template, generates a plan that ensures compliance with class rules and statutory regulations. 

We have issued a reminder to ship owners: a Statutory Retroactive Requirement note (RR) in the ship’s profile of “MyDNV – Fleet in service”. It details the date the ship is required to be in compliance with the D-2 standard (i.e. installation and utilization of a BWTS: RR Ref 1034f and RR Ref 1034g).

DNV GL has gained substantial knowledge about treatment system technologies through the type approval of BWTS for IMO and USCG, and we utilize this knowledge during installation and retrofit projects.

Related downloads and links


DNV rules for BWM

Access DNV Rules for Ships Pt.6 Ch.7 Sec.1 on the DNV Rules and Standard Explorer


Guide to approval of retrofit ballast water management system installations

Download the PDF


BWM plan Generator (customer only)

Access via the customer portal


Biological testing at commissioning of BWM

Download the template as word file

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General contact for Ballast Water Management