D-1 (exchange standard) requires that at least 95% of the original ballast water is replaced during the exchange. D-2 (performance standard) requires that discharged water contains fewer than 10 viable organisms per m³ greater than 50 µm and fewer than 10 viable organisms per mL in the 10–50 µm size class. All ships must now meet D-2 using an approved Ballast Water Management System (BWMS) under the BWM Convention as amended by MEPC.325(75).

MEPC.288(71) adopted the 2016 Guidelines for Ballast Water Record Book entries under Regulation E-2. Masters must record every ballast water operation: uptake, exchange, and discharge — including position, volume, salinity, temperature, and method used. Entries must be made promptly and are subject to port state control inspection for at least two years.

The flow-through (dilution) method pumps open-ocean water in through the bottom while simultaneously discharging from the top. Because the tank is not emptied and the mixing is imperfect, three full tank volumes must be exchanged to statistically achieve 95% replacement of original organisms — the mathematical basis stems from the USCG flow-through model and is codified in BWM Regulation B-4.

BWM Convention Regulation B-4 requires exchange to be performed at least 200 nautical miles from the nearest land and in water at least 200 metres deep. Where a ship cannot meet these conditions (short coastal voyages), the ship must follow the approved Ballast Water Management Plan and port state requirements may specify alternative exchange areas.