Ultraviolet Sterilization. Radiation that has a wavelength shorter than visible light. It is often used to kill bacteria and destroy ozone. Ultraviolet sterilization is considered safe when exposed to humans and possesses very few limitations. Such limitation exists in unfiltered water that consists of microbes which hide inside suspended solids and help protect them from the intensity of UV lights. As a result, ultraviolet sterilization is most efficient in purifying water after it has already gone through a filtration phase.