Internal BW transfers and using open ocean water are methods by which container ships can avoid water removal during transfer operations. Flow-through process is another method where water is continuously cycled through the ballast tank to avoid traditional discharge.
During a transfer operation, water removal from the tanks is not required when the vessel utilizes internal ballast water (BW) transfers to maintain stability, rather than discharging the ballast water. Internal transfers are an efficient management approach, enabling container ships to avoid ballast water exchange (BWE) under certain conditions. These ships can also entrain ballast water from open ocean sources which are less likely to require exchange due to the biological composition of the water, compared to coastal waters.
Another method to avoid water removal is the flow-through process, where water is drawn into the tank and flushed out, ensuring at least 300% of the tank's capacity is pumped through to sufficiently dilute and remove coastal organisms.