Ultraviolet light is a relatively new method of disinfecting private water systems. Ultraviolet radiation adds nothing to the water and does not produce any taste or odor. The UV light is produced by a mercury vapor lamp which produces a disinfecting dose rated in microwatt-seconds per square centimeter (MWs/cm2). Values of 20,000 MWs/cm2 will kill most types of pathogenic bacteria. However, viruses are more resistant and variable and may need up to 45,000 MWs/cm2.
An ultraviolet water treatment device is quite simple. The most common design consists of a stainless cylindrical chamber with a cylindrical mercury arc lamp located in it. Lamps vary in length from 12 to 48 inches and thus vary in energy output. Water enters one end of the chamber, flows through the chamber around the lamp and exits the other end within a few seconds.
Advantages of Ultraviolet lights:
Effective - All micro-organisms are susceptible to ultraviolet disinfection.
Economical - Thousands of liters can be purified.
Safe - No danger of overdosing, no addition of dangerous chemicals.
Fast - Water is ready for use as soon as it leaves the purifier - no further contact time required.
Easy - Simple installation and maintenance. Compact units require minimum space.
Automatic - Provides continuous or intermittent disinfection without special attention or measurement.
No Chemicals - No chlorine taste or corrosion problems.