There are advantages and disadvantages to UV water treatment technology. Advantages: easy to use, no chemical corrosion and nothing is added to the water. Disadvantages: There is no residual going into the water distribution network and it will not treat the biofilm which is where Legionella is known to grow and cause eventual Legionella outbreak. Additionally, UV technology requires filtration prior to the UV lights to remove any micro particles. That said, UV technology can be used as a complimentary technology to a CSI solution yet should not be relied upon as a primary technology to treat biofilm contamination against Legionella contamination.