They work by irradiating invasive organisms to prevent reproduction. UV systems are a user-friendly option and work in all water salinities. They also have a relatively small footprint in comparison to other systems and do not produce any by-products. However, a possible drawback is that the USCG regulation currently requires organisms to be dead before ballast water is discharged. In the near future, this regulation may change and be harmonised with the IMO regulation, which would accept sterilization as a treatment method. In theory, UV systems are suitable for any type of vessel. Although they are more commonly installed on ships with relatively low ballast requirements, such as passenger ships, and supply vessels, they are also versatile enough to be successfully deployed on larger vessels such as Panamax containerships.