IMO BWM Convention · D-2, MEPC.369(80) & USCG 33 CFR 151
Ballast Water Management (BWM D-2) & Ballast Water Record Book Guide
Since 8 September 2024, every ship subject to the IMO Ballast Water Management (BWM) Convention has been required to meet the Regulation D-2 biological performance standard using an approved Ballast Water Management System (BWMS). Furthermore, from 1 February 2025, IMO Resolution MEPC.369(80) and BWM.2/Circ.80 introduced the revised Code A–H Ballast Water Record Book (BWRB) format.
In 2026, discrepancies between the BWMS electronic PLC data logger, the Ballast Water Record Book, and the ship’s approved Ballast Water Management Plan (BWMP) are among the fastest-growing triggers for PSC Action Code 17 / 30 findings, USCG COTP restrictions, and SIRE 2.0 / RightShip RISQ 3.2 observations.
Updated · Written by SeaReady in our own words. Not affiliated with OCIMF, RightShip, CDI, any MoU or any administration — always check the current official documents.
1. BWM Convention Standards: D-1 vs D-2, MEPC.300(72) & MEPC.369(80)
Under the International Convention for the Control and Management of Ships’ Ballast Water and Sediments, 2004 (as amended), ships of 400 GT and above must carry an International Ballast Water Management Certificate (IBWMC), an approved ship-specific Ballast Water Management Plan (BWMP), and a Ballast Water Record Book (BWRB):
| BWM Requirement / Instrument | Mandatory Limit / Retention | Operational & Inspection Rule |
|---|---|---|
| Regulation D-1 (Ballast Water Exchange Standard) | ≥ 95% volumetric exchange (or 3× tank volume pumping-through) | Carried out ≥ 200 nm from the nearest land and in water ≥ 200 m deep (or ≥ 50 nm / ≥ 200 m where 200 nm is impossible). From 8 September 2024, D-1 exchange is no longer accepted as the routine compliance method for existing ships required to meet D-2, except under an approved contingency measure when the BWMS fails. |
| Regulation D-2 (Ballast Water Performance Standard) | < 10 viable organisms/m³ (≥ 50 µm) and < 10 viable organisms/mL (10–50 µm) | Mandatory biological discharge standard for all ships subject to the BWM Convention after their IOPP renewal window (and universally from 8 September 2024), plus indicator microbe limits for Vibrio cholerae (< 1 cfu/100 mL), E. coli (< 250 cfu/100 mL) and Intestinal Enterococci (< 100 cfu/100 mL). |
| BWMS Code (IMO Res. MEPC.300(72)) & Commissioning Testing (MEPC.325(75)) | Mandatory biological indicative/detailed sampling at installation | Requires every newly installed Ballast Water Management System (BWMS) to hold an International BWMS Code Type Approval Certificate and undergo biological commissioning testing (Regulation E-1.1.1 / BWM.2/Circ.70/Rev.1) before the International Ballast Water Management Certificate (IBWMC) is issued. |
| Ballast Water Record Book (BWRB — Regulation B-2 &Res. MEPC.369(80)) | Retained on board ≥ 2 years, then in Company control ≥ 3 years | Amended Appendix II BWRB format (IMO Res. MEPC.369(80), effective 1 February 2025, alongside BWM.2/Circ.80 guidance) requires detailed itemised entries under Codes A through H for every uptake, internal transfer, treatment, exchange, discharge, sediment disposal and accidental/contingency operation. |
2. Revised Ballast Water Record Book (BWRB) Codes A–H (MEPC.369(80) & BWM.2/Circ.80)
Under IMO Resolution MEPC.369(80) (in force 1 February 2025) and BWM.2/Circ.80, every ballast operation must be recorded chronologically using standardized letter codes (A to H), signed by the officer in charge of the operation, and countersigned on every completed page by the Master:
| BWRB Code | Operation Category (MEPC.369(80) Appendix II) | Mandatory Details to Record |
|---|---|---|
| Code A | When ballast water is taken on board (Uptake) | Record date, time, port or lat/long, estimated volume (m³), tank identity, water depth, and whether the BWMS was operated during uptake per the Type Approval Certificate. |
| Code B | Whenever ballast water is circulated or treated for BWM purposes | Record internal tank-to-tank circulation, re-treatment before discharge, or chemical neutralisation dosing, with start/stop times, tank IDs and volume treated (m³). |
| Code C | When ballast water is discharged into the sea | Record date, time, port or lat/long, volume discharged (m³), remaining volume in tanks, and confirmation that the BWMS operated within Total Residual Oxidant (TRO) or UV-intensity design limits. |
| Code D | When ballast water is discharged to a reception facility | Record date, time, port, reception facility name, volume discharged (m³), and attach the shore reception receipt. |
| Code E | Accidental or other exceptional uptake or discharge of ballast water | Record date, time, location, tank IDs, volume (m³), reason for the exceptional discharge or BWMS bypass, and the contingency measures agreed with the Port State under BWM.2/Circ.62. |
| Code F | Additional operational procedures and general remarks | Record BWMS filter differential-pressure flushing issues, UV lamp or TRO sensor faults, challenging water quality (CWQ / high turbidity) operations under MEPC.387(81), and calibration checks. |
| Code G | Sediment management (cleaning, removal & disposal) | Record routine ballast tank sediment flushing, stripping at sea, or sediment removal during dry-docking / tank entry with disposal receipts. |
| Code H | Exemptions or equivalencies granted | Record any Regulation A-4 exemption or flag/port equivalency details. |
- Electronic Ballast Water Record Books (MEPC.372(80)): If your vessel uses an electronic BWRB, it must be approved against IMO Resolution MEPC.372(80) and carry a vessel-specific Flag State Written Declaration on board.
- Tank-by-tank volume accuracy: Never record nominal 100% tank capacities in the BWRB if the tanks were only filled to 85% or stripped to 15 m³. Inspectors compare the BWRB m³ figures against the BWMS flow-totaliser reading and the daily tank sounding log.
3. UV, Electrochlorination & Chemical BWMS Checks on Deck and in the Engine Room
During an engine-room or pump-room tour, PSC, USCG, SIRE 2.0 and RightShip inspectors ask the Chief Officer and responsible Engineer to demonstrate the BWMS and verify its safety interlocks:
- UV-based BWMS checks: Verify that the automatic self-cleaning filter differential-pressure switch operates properly, UV lamp hours and UV intensity sensors (W/m² or %) are within the Type Approval System Design Limitations (SDL), quartz sleeves and wiper mechanisms are clean, and temperature shutdown interlocks are tested.
- Electrochlorination (EC) & chemical-injection BWMS checks: Confirm that Total Residual Oxidant (TRO) sensors are calibrated with fresh DPD reagents within their 12-month calibration window, neutralisation chemical tanks (e.g. sodium thiosulphate / sodium bisulphite) hold sufficient stock for a full deballasting cycle so discharged water stays below the Maximum Allowable Discharge Concentration (MADC, typically ≤ 0.1–0.2 mg/L Cl₂), and hydrogen (H₂) gas extraction blowers and H₂ gas detectors in the BWMS room operate with functioning interlocks.
- Challenging Water Quality (CWQ — IMO Res. MEPC.387(81)) & Contingency Measures (BWM.2/Circ.62): When ballasting in high-turbidity or low-salinity river/estuarine ports where the BWMS cannot maintain design UV transmittance or conductivity, follow the approved CWQ and contingency steps in the BWMP, log the exact alarm codes in the BWRB under Code E / Code F, and notify the next port State before entering port waters so any post-uptake exchange/flushing is pre-approved.
Questions seafarers ask
What changed in the Ballast Water Record Book (BWRB) format on 1 February 2025 under IMO Resolution MEPC.369(80)?
IMO Resolution MEPC.369(80) replaced the original Appendix II Ballast Water Record Book layout with a much more structured, code-lettered format (Codes A through H, mirroring the MARPOL Oil Record Book style) accompanied by IMO Circular BWM.2/Circ.80 on harmonized BWRB record-keeping. Port State Control officers now check that the vessel carries the updated MEPC.369(80) BWRB (or an approved electronic BWRB under MEPC.372(80)) and that entries match the BWMS data logger.
What must the Master do if the Ballast Water Management System (BWMS) fails or encounters Challenging Water Quality (CWQ)?
Under IMO Circular BWM.2/Circ.62 (Guidance on Contingency Measures) and Resolution MEPC.387(81) (Interim Guidance on Challenging Water Quality), the crew must never silently bypass the BWMS or falsify records. Instead, follow the ship-specific contingency procedure in the approved Ballast Water Management Plan (BWMP): record the alarm and fault in the BWMS log and BWRB (Code E / Code F), notify the Flag Administration and the next Port State authority (such as the USCG COTP / EPA or AMSA MARS) BEFORE arrival, and request authorization for a contingency measure (such as D-1 mid-ocean ballast water exchange plus flushing at >200 nm / >200 m depth).
How do USCG VGP/VIDA and Type Approval rules differ from standard IMO D-2 compliance?
Ships discharging ballast in United States waters (within 12 nm) must use a USCG Type Approved BWMS (or hold a valid USCG extension / Alternate Management System acceptance), submit the mandatory Ballast Water Management Report to the National Ballast Information Clearinghouse (NBIC) no later than 6 hours after arrival (or prior to arrival from Canada/Mexico), calibrate BWMS sensors annually under 33 CFR § 151.2075, and conduct biological efficacy and residual biocide monitoring required by the EPA Vessel General Permit (VGP / VIDA).
Why do Port State Control and SIRE 2.0 inspectors cross-check the BWMS PLC data logger against the BWRB?
Every Type Approved BWMS stores at least 24 months of electronic operational logs in its PLC (recording UV intensity or TRO ppm, flow rate in m³/h, filter backflush pressure, GPS position and bypass valve movement). During PSC, USCG, SIRE 2.0 (Chapter 6) and RightShip RISQ (Section 13) inspections, the inspector asks the Chief Officer or 2nd Engineer to open the BWMS HMI history screen and compares the last three ballasting/deballasting operations against the handwritten or electronic BWRB entries and sounding logs.
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Related guides
- Oil Record Book & Garbage Record Book guideORB Part I codes (C, D, E, G, H, I), Garbage categories A–K, Ballast Water and e-logbook rules.
- USCG port state control checklistHow the USCG picks ships, the 96-hour NOA, ballast, ECA, security and the exam.
- PSC inspection checklistThe inspection start to finish, every deficiency area, risk windows and the CIC.
- RightShip inspection checklistThe 17 RISQ 3.2 sections, how the inspection day runs, what changed in 3.2 and the age-trigger dates.