Ultraviolet Light (UV)

Ultraviolet light has treated water since the beginning of time through natural sunlight. Its nature’s way of killing bacteria. UV disinfection of water is now one of the most popular systems. With the development of new materials and commodity production of components, UV units are increasingly being used in household, industrial and commercial applications.

UV, like distillation, disinfects water without adding chemicals, and therefore possesses some of the same benefits as distillation. It does not create new chemical complexes, nor does it change the taste or odor of the water, and does not remove any natural beneficial minerals in the water.

The design of the UV unit is quite simple. Its main component is the UV light source, which is enclosed in a transparent quartz or Plexiglas protective sleeve. It is mounted so that water can pass through a flow chamber, and UV rays are admitted and absorbed into the stream.

The UV light destroys the genetic material of pathogens like coliform bacteria and legionella, which effectively neutralizes them by preventing them from reproducing. UV is not fully effective for the treatment of hard-shelled cysts like Cryptosporidium and Giardia lamblia (see the chart for details on UV energy level required and the list of pathogenic and indicator organisms destroyed by it, page 14).

UV devices are most effective when the water has already been partially treated, and only the cleanest water passes through the UV flow chamber. UV devices are therefore often combined with other technologies such as pre-filters, carbon filters, and reverse osmosis systems to provide complete water quality solutions. Suspended solid particles and organic matter can shield organisms against the light, which is why it is essential to pre-filter the water.