Worldwide fleet has continuously been growing during last years, using ballast water almost all of the vessels and increasing the risk of spread of invasive species into local environments. The risk of invasion has pushed the International Maritime Organization to legislate the control and treatment of ballast water to minimize the risks. For this reason, the International Convention for the Control and Management of Ships’ Ballast Water and Sediments has played an essential role for achieving a proper control of the ballasting and de-ballasting process. After the different regulations included on the Convention, many Ballast Water Management Systems (BWMS) have been approved. The different treatment systems have clearly reduced ballast water impact but the only way for reducing completely the risk of invasion is to reduce the use of ballast water and to design alternative methods. Therefore, the international organizations should act for accomplish the reduction of ballast water usage in the near future and to motivate maritime industry to invest and to study new free-ballast vessel design. The methodology used during the paper consists on a deep theorical explanation of the ballast water impact (including Ballast Water Management Convention) and a comparison among four different BWMS. The aim of the comparison is to distinguish which system is best regarding the friendliness to the environment and the efficiency for the vessel. After the comparison, different proposals for improving the ballast water impact will be explained to understand how the risk can be even more reduced.