Ultra violet works to disinfect water because light rays with wavelengths of 240-280 nanometers destroy 99.9% of the crucial DNA of viruses and bacteria that prevents them from reproducing.
It is an excellent natural means to purify water without resorting to harsh or toxic chemicals and works to eradicate even Giardia and Cryptosporidium parasites that are often very resistant to chemical disinfection. Clearing your water of these types of drug-resistant water-borne parasites is particular important for young children, seniors, and anyone whose immune system is compromised in any way who may be more susceptible to the type of illnesses they can cause.
Ultra violet sanitization is also a good way of disinfecting well water and other water sources that do not contain chlorine or other cleansing chemicals.
Ultra violet water disinfection does not remove potentially beneficial minerals, or change the odor or taste of the water in any way, and if installed early in your system can help to prolong the life of other types of filters by reducing the need to clean and flush your system so often.