The fundamental difference between BOS Natural Ballast and other ballast water treatment systems (BWTS) is that there is less aggressive treatment.

BOS Natural Ballast measures and records all ballast water management parameters continuously. Typical BWTS assumes operational compliance once type-approved. This may not be true since ships take ballast water from all corners of the oceans. BOS Natural Ballast verifies that the ballast water management system meets the ballast water discharge standard at all times.


There is plenty of water out in the mid ocean that meets the ballast water discharge standard. There is definitely more compliant than non compliant water as otherwise us humans would be in serious trouble.

BOS Natural Ballast ensures that the uptake water is compliant and therefore the water can be discharged. However, in case there is no compliant water available during the uptake the ship has the option to uptake ballast at the port but to flush the non-compliant ballast water later at mid ocean

BOS Natural Ballast provides continuous sampling. It is a quick and reliable way of testing  to ensure that the uptake and discharge ballast water are always compliant. 

The system does not assume compliance; it positively and actually ensures that ballast water meets the standard at all times. 

It is true that some regrowth has been experienced by projects after treating the ballast water by some type-approved BWTS. However, such BWTS generally do not monitor the ballast water after treatment. They generally assume the compliance after treatment which may not be true. BOS Natural Ballast measures, record and verifies compliance continuously.  Therefore, regrowth is not possible. Otherwise, the D2 standard itself should be revised. 

BOS Natural Ballast does not have treatment process which requires different energy levels to treat different ballast water capacities and flow rates. BOS Natural Ballast automatically and continuously samples the ballast water at a constant rate (about 10 cu m/hr) no matter what the ballast water capacities and flow rates to achieve one size fits all ship sizes and types.

Furthermore, the sampling pump required by the system to sample at a constant is less than 10kW. 

In such situations, the “Same Risk Area” or “Same Captain of the Port Region” guidelines may apply and mandatory BWMS may be waived.

*refer also to FAQ “what if there is no compliant water”