Ultraviolet light is invisible, electromagnetic energy with wavelengths between visible light and x-rays. Ultraviolet is that band of light located in the spectrum between 200-300 nanometer wavelength. UV light has long been acknowledged as a means of disinfection because of its ability to kill microorganisms by penetrating their outer membrane and impairing proper DNA function.
The most effective germicidal range is at 253.7nm for destroying microorganisms. A UV disinfection system transfers electromagnetic energy from a mercury arc lamp to an organism's genetic material. The intensity of ultraviolet is expressed in microwatt seconds per square centimeter and is the product of the lamp output in watts, the length of time exposure and volume of water being treated.