Integration with the vessel Automation and Control system is a critical milestone in a Ballast Water Treatment System (BWTS) retrofit project. When completed properly, it provides for simple and intuitive operation of the BWTS and supports compliance with ballast water regulations. Integration results in seamless operation and monitoring of the ballast pumps and valves together with the BWTS at control stations in the Engine Control Room and/or bridge. It provides appropriate interlocks and alarms to ensure that the BWTS is not bypassed through ship’s valves, which are not controlled and monitored by the BWTS. It also encourages and supports the required log entries in the Ballast Water Logbook. A structured approach to this integration work results in fleet wide consistency, providing maximum benefit to the owner by reducing the risk of non-compliance as well as reducing the future cost of technical support and training.