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This project is just one example of research through NIFA and the Land Grant System that has the opportunity to positively impact drinking water quality. Please check back periodically for other highlighted programs.

Ultraviolet Light Disinfection of Drinking Water: An Alternative to Chlorination

Researchers have found that UV light disinfection is an effective treatment to inactivate waterborne pathogens in point-of-use drinking water systems.


Although chlorination has been a very successful water disinfection technique, chlorine in drinking water has been linked to a number of health problems. Since mid-1970s, formation of trihalomethanes as a result of chlorination of natural waters has been documented (Symons et al., 1975; Rook et al., 1974 and Bellar et al., 1974). Trihalomethanes are possible human carcinogens as characterized and pose a potential human health threat (USEPA, 1997). In addition, people often dislike the taste and smell of chlorinated water. Unlike chlorination, ultraviolet (UV) irradiation processes pose no known carcinogenic disinfection by-products (Zoeteman et al., 1982; Whitby et al., 1984; Kool et al., 1985; Kruithof et al., 1989; Rein et al., 1992 and Oppenheimer et al., 1997) and produce no tastes and odors. Researchers are exploring safe alternative drinking water disinfectant treatments.


A research team from the Center for Water Quality external link (O.S. Mbuya and C.S. Gardner) and the Dept. of Biology (L.A. Latinwo) at Florida A&M University and Teknikon North Gauteng, South Africa (B.J. Mankazana) examined the effectiveness of UV light to inactivate waterborne pathogens (e.g., Escherichia coli, Streptococcus faecalis,Salmonella typhi and Shigella flexneri) under laboratory conditions.

before & after image showing success of UV light disinfection


Results have shown that UV light irradiation reduced bacterial counts in water to non-detectable levels. UV irradiated bacteria did not photoreactivate when exposed to visible light for 24 hours. However, water turbidity decreased the disinfecting effectiveness. These results suggest that UV light disinfection is appropriate for point-of-use drinking water systems. There is potential application of these UV light drinking water disinfection systems in rural communities and developing nations. Work is being undertaken to develop and apply low-cost UV disinfection technology to drinking water supplies in Tanzania and South Africa.


For more information on this project, contact O.S. Mbuya.
A paper on this work by Mbuya et al. is in review at the Journal of Environmental Quality external link.

Please visit the NIFA Drinking Water and Human Health theme page for more information.

References cited:

Bellar T.A.; Lichtenberg J.J.; Kroner R.C. The Occurrence of Organohalides in Chlorinated Drinking Water. Jnl. Am. Water Works Assoc. 66(22), 703-706.

Kool H. J.; Kreijl, C. F.; Hrubec J. (1985). In Water Chlorination: Chemistry, Environmental Impact and Health Effects, Vol. 5.

Kruithof J. C. et al (1989). Summaries, WAS. SER BERLIN 1989; International Ozone Association, European Committee: Paris, 1989; pp.III-3-1-15.

Oppenheimer J. A., Jacangelo J. G., Laine J., Hoagland J. E. (1997). Testing the equivalency of ultraviolet light and chlorine for disinfection of wastewater to reclamation standards. Wat. Environ. Res., Vol. 69, Number 1

Rein D. A., Jamesson G. M., Monteith R. A. (1992). Toxicity Effects of Alternative Disinfection Processes. Proc. 65th Annual. Water Environ. Fed. Conf. Vol. X Facility Manage., New Orleans, La., 461.

Rook J.J (1974). Formation of Haloforms during Chlorination of Natural Waters. Wat. Treatment. Exam. Vol. 23(2), 234-243.

Symons J.M; Bellar T.A.; Carsewell J.K.; DeMarco J.; Kropp K.L.; Robeck G.G.; Smith B.L.; Stevens A.A (1975). National Organic Reconnaissance Survey for Halogenated Organics. Jnl. Am. Water Works Assoc. Vol. 67, 634-647.

U.S. Environmental Protection Agency (1997) Integrated Risk Information System (IRIS). Office of Research and Development.

Whitby G. E., Palmateer G., Cook W. G., Maarschalkerweerd J., Huber D. and Flood K. (1984) Ultraviolet Disinfection of Secondary Effluent. J. Wat. Pollut. Control Fed. 56, 844-850.

Zoeteman B. J. C. et al., (1982) Environmental Health Perspect. 46, 197-203.