Ballast water is absolutely essential to the safe and efficient operation of modern shipping, providing balance and stability to un-laden ships. However, it may also pose serious threats to ecology, economy and health.

There are thousands of marine species that may be carried in ships' ballast water, basically anything that is small enough to pass through a ship's ballast water intake ports and pumps. If these organisms survive transport to other parts of the globe, their impact can be devastating. Such invasions can jeopardize the local ecosystem, and even pose threats to human health. Usually, their effects are irreversible.

The introduction of invasive marine species into new environments by ships' ballast water, attached to ships' hulls and via other vectors has been identified as one of the four greatest threats to the world's oceans.In 2004, IMO adopted the International Convention for the Control and Management of Ships' Ballast Water and Sediments, which will phase in requirements for ballast water treatment by 2020 at the latest.