By Chanda Morrow

Summary: This article provides information to better remove the mystery for consumers from UV technology to not only enhance its selling potential but to inform them of the benefits from this cutting edge disinfection technology.

Scientists and ecologists throughout the world are making a conscious effort to protect source water through both conservation and generation of awareness to drinking water threats. Despite their efforts, formerly unknown microorganisms continue to be identified and pollutants continue to contaminate rivers, lakes and groundwater that supply the world’s drinking water. Due to more information availability on water quality issues and uncertainties of source water protection, consumers have reached for point-of-use/point-of-entry (POU/POE) systems to ensure safe drinking water in their homes and businesses.

Ultraviolet light (UV) is just one of the technologies emerging as a popular disinfection method to treat drinking water. The application of UV technology in municipal water systems as well as in POU/POE applications is increasing in popularity as evidence of its efficacy against well-known waterborne pathogens becomes better documented.

Those of us in the water industry know that UV is highly effective in protecting consumers from potentially harmful microorganisms. However, the term “ultraviolet irradiation” is intimidating to many consumers, much in the way “microwave” was in the 1970s and early 1980s. When people don’t understand how a technology works, they may perceive it as potentially harmful. Explaining and marketing UV to the consumer is the challenge. Keeping it simple is the key.

Saying how it works
First, you’ll need to explain how “ultraviolet” or “UV” is at the shorter end of the electromagnetic light spectrum and is not visible to the naked eye. The bluish-purple illumination from the UV that can be seen is an effect and not the actual UV. UV doesn’t pose any chemical threats because there’s nothing except energy rays added to the water. And it doesn’t induce taste and odor problems.

Second, it’s important to explain how UV is going to be transmitted into the water supply. A lamp is what produces the UV energy. Typically, a highly transmissive quartz sleeve is used as a protective shield for the lamp itself. Other options for UV transmission into water are to use polycarbonate or Teflon sleeves to surround the lamp.

For your information, UV is generated at 185 nanometer (nm) and 254 nm wavelengths in most water treatment applications, with the higher level optimal for germicidal disinfection. UV intensity, or dosage, is a measure of the energy expended over a certain area over a certain period of time, described as milliwatt seconds per square centimeter, or mWs/cm2. This is equivalent to milliJoules per square centimeter, or mJ/cm2, another measurement named after English physicist James Prescott Joule (1818-89). Much of this, however, may go over a consumer’s head and/or make their eyes glaze over during your presentation.

Keep your explanation of the process simple. Water flows through the area between the UV quartz sleeve and the chamber wall. When the UV lamp is illuminated, UV energy is transmitted through the protective sleeve and into the water, irradiating the microorganisms it contacts. Sufficient irradiation will inactivate waterborne microorganisms.

What does UV destroy?
Through this disinfection process, microorganisms are inactivated. Their DNA structure is altered by the irradiation, prohibiting reproduction. Bacteria, including heterotrophic or HPC components, viruses, parasites, yeast, molds and protozoa are among the contaminants reduced through application of UV. Some microorganisms are resistant to UV disinfection, particularly if they have a hard protective cell structure or are shielded by other particles or attached together in groups. And many inorganic and organic contaminants will be unaffected, necessitating an additional treatment method. This brings us to the important pre-treatment stage.

Combining treatment technologies
Most water treatment systems that incorporate UV also use additional technologies to both increase the effectiveness of the UV light and to reduce other classes of contaminants. To improve UV performance, pretreating the water before exposure is often necessary.

By using a carbon filter in pre-treatment, sediment and large particles are trapped. If a pretreatment filter is not used, sediment and particles may block the UV and hinder the light’s ability to inactivate microorganisms. Thus, microorganisms are allowed to pass through the system untreated.

Determining the correct filter size depends on the characteristics of the incoming feedwater traveling into the UV disinfection process. Turbidity levels, hardness and iron content, and bacterial contamination in the inlet water must be considered—as well as the temperature and flow rate—when evaluating UV filtration systems. Turbidity is the amount of small particles of solid matter suspended in water as measured by the amount of scattering and absorption of light rays caused by the particles; it blocks light rays and makes the water opaque.
Some examples of mediums used in combination with UV light:

  • Granular activated carbon filters
  • arbon block filters
  • Sediment filters

Advantages of combinations
Consumers become aware of water quality issues via national and local media. Most notable in the news are microbiological contaminants such as E. coli, Salmonella and Listeria that can cause illness within a day or two of being ingested. UV helps address consumers’ concerns by inactivation of these and other microorganisms.

According to the Water Contamination Solution chart of the Water Quality Association, UV is a recommended water treatment method for reducing coliform bacteria. Recent studies have also shown that UV is an effective treatment method for problematic microorganisms such as Cryptosporidium and Giardia lamblia cysts and oocysts.

Compared to the complexity of distillation and reverse osmosis, UV systems are relatively inexpensive and are easily serviced and maintained. Introducing a UV system to your product mix allows you to offer customers a long-lasting, reliable and non-chemical water treatment system at an affordable price.

Marketing UV systems
Although important, consumers rarely want to hear about the technical aspects of UV treatment. Such facts as its ability to re-arrange electrons to destroy microorganisms’ cytoplasmic structures in order to prevent reproduction, that the germicidal wavelength of UV is 254 nm, specifics of flow rates and disinfecting dosage of 16,000 microwatt-seconds per square centimeter will make their heads spin. Again, concentrating on these UV characteristics may lose customers.

Knowing these technicalities help water treatment professionals provide the means to invent the best quality technology for consumers. Education on the types of technology, combining treatment methods and the overall benefits of “drinking quality water and plenty of it” will actually enhance the consumer’s desire to make a change and look further into alternatives to tap and bottled water.

In order for ultraviolet disinfection treatment methods to be effective, there are many factors that need testing and constant monitoring. Of primary importance is knowing the composition of water entering the POU system. Combining the right filters with UV can enhance the effectiveness of the system by removing a broader range of interfering contaminants. When maintained properly, a UV-combination POU system provides consumers with an effective means to treat contaminants, low maintenance for the water treatment dealer and quality drinking water for the consumer—a valuable investment in their peace of mind.

The author would like to thank Jenny Christensen, Bob Haney and Tom Weekly from innowave, Jim Nolan from Mutual of Omaha and to Joe Harrison, WQA technical director, for aiding in the evolution of this article and providing feedback and comments. Also, to Tyler Adam from innowave for artwork additions and CAD drawing as seen in Figure 2.


  1. ANSI/NSF Standard 55, “Drinking Water Treatment Units—Ultraviolet Microbiological Water Treatment Systems,” NSF International, Ann Arbor, Mich.
  2. “Improving the Quality of Water Through Disinfection,” Water Quality Association, Lisle, Ill., WaterReview Technical Brief, Volume 6, No. 1, 1991 and 1995.
  3. Harrison, J.F., and W. McGowan, WQA Glossary of Terms, 3rd Ed., Water Quality Association, Lisle, Ill., 1997.
  4. Bolton, J.R., and L.R. Henke, “Ultraviolet Disinfection: A Basic Primer,” WC&P, April 1999, pp. 34-38.
  5. Hargy, T.M., “Ultraviolet Light Found to be Effective Against Cryptosporidium,” Water Technology, September 1999, pp. 63-67.
  6. Eccleston, Bruce, “UV Intensity Levels Affected by Water Quality,” Water Technology, May 1998, pp. 61-68.
  7. Baird, M.T., “UV Teams with Filtration for Effective Conditioning,” Water Technology, October 1997, pp. 78-82.
  8. Webb, Eric, “For Potable Water, Ultraviolet Shines,” Water Technology, June 1996,
    pp. 88-92.
  9. Ingram, Colin, The Drinking Water Book: A Complete Guide to Safe Drinking Water, Ten Speed Press, Berkeley, Calif., pp. 90-91
  10. Lewis, S.A., The Sierra Club Guide to Safe Drinking Water, Sierra Club, San Francisco,
    p. 67
  11. “Disinfection by UV-radiation,” Philips Lighting, Philips headquarters, Europe.

About the author
Chanda Morrow is a marketing coordinator for innowave inc., a Mutual of Omaha subsidiary. innowave markets UV and distillation-based water treatment systems for business and residential markets. The company is a Water Quality Association member and has dealers across the United States and Canada. She can be reached at innowave inc., 3201 Farnam St., Omaha, Neb. 68131, (800) 723-3426, or email: More information on innowave can be found at


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