An ultraviolet purifier kills microorganisms in water using strong light waves. Instead of chlorine or other harsh chemicals, an ultraviolet purifier can eliminate bacteria, viruses, and mold from well water for residential properties that aren't on a municipal supply. These provide an inexpensive yet effective way to prevent your family from getting dysentery, diarrhea, E. coli, and other infections from drinking water.
An ultraviolet water purifier is simply a light bulb suspended in a pipe that carries water from a well or reservoir to your faucets. Ultraviolet rays emit a certain kind of high-energy light that isn't visible to human eyes. The light holds so much energy that when microorganisms are exposed to it, even for a brief time, they are irreparably damaged. Viruses, fungi, bacteria, yeast, and mold are all adversely affected.
![](http://images.wisegeek.com/slideshow-mobile-small/salmonella.jpg)
The ultraviolet light bulb, just like regular light bulbs, screws into a socket and uses a small amount of electricity. But the actual bulb must be constructed from quartz, because glass filters out that part of the spectrum. Unlike other incandescent bulbs, the ultraviolet light that's generated is very dangerous if you look at it or let it illuminate your skin. Therefore, a metal sheath encloses the light mechanism.
![](http://images.wisegeek.com/slideshow-mobile-small/isolated-glass-of-clear-liquid.jpg)
An ultraviolet filter will either be located at the point of entry or at the point of use. Point of entry filters affect all the water flowing into your house, whether it's going to wash a load of laundry or fill the dog's water dish. A point of use filter fits right underneath a faucet or appliance. Thus, you can decide to only filter water that's likely to get in your mouth by filtering the kitchen faucet, and not other places, like the garden hose. An audible alarm tells you if the filter ever stops operating.
If your source of water is completely unpurified, you may need to install other levels of purification before killing microorganisms. An ultraviolet purifier can be combined with a sediment filter or a water softener to improve the quality of water. Germicidal ultraviolet rays all but totally eliminate the risk for hepatitis, salmonella poisoning, typhoid fever, dysentery, E. coli, diarrhea, and other infections caused by live microorganisms. It will not affect chemical additives, salt, minerals, or the taste of water.