Ballast water treatment systems remove and destroy both biological and non-biological substances from ballast water. This article reviews the importance of ballast water treatment systems, some common methods, industry regulations, and selecting the ideal method. Importance of Ballast Water Treatment Systems Since the advent of steel-hulled ships, water continues to serve as ballast to stabilize ships, especially when not fully laden. This practice reduces stress on the hull, provides transverse stability, as well as improves propulsion and maneuverability. In addition, ballasting compensates for weight changes in cargo loads and fuel levels. However, ballast water often contains a plethora of organisms from