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 which 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 Cryptosporidia 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.
An ultra violet bulb contained in a water-tight stainless steel tube burns constantly, irradiating the water with its purple light. Water flow is reduced to just 0.5 GPM which allows time for the ultraviolet disinfection process to take effect. The ultra violet bulbs are designed to give 9,000 hours of continuous use which in practice means you will need to change it about once a year. When the bulb does burn out, an alarm sounds to alert you to change it.