Microbiological contamination should not be present in many water related production industries along with drinking and potable water sources. Bacteria, viruses, algae, etc cause serious health problems for people. They also create troubles for some delicate businesses such as cosmetics, pharmaceutical and beverage.
For these reasons the water should be properly disinfected. Natural Ultraviolet (UV) rays comes from the sun.  UV spectrum is higher in frequency than visible light It is also lower than the  x-ray’s. It means that the Uv lights has a longer wavelength.  As a water treatment technology, UV is a good disinfectant due to its strong germicidal affets. 
They are very economical and reliable products since they do not require any Chemicals or consumables. Only disadvantage is that the system should be mounted at the very close to end use. After UV disinfection the water should not be travelling for a long distances. 
There is a time-meter on the UV panels. Average time of the UV lamp is 9000 hours. The lamp should be replaced after compliting its lifetime.