One of the world's most serious health problems is the lack of safe drinking water in developing countries. By some estimates, up to two billion people cannot get clean water. Diarrhea, cholera, hepatitis, and other diseases caused by contaminated water kill some five million people a year, including three million children. Many times that number get sick, and the growth of 60 million children is stunted because of recurring diarrhea and other illnesses.
Although the problem is well-known, it has not been easy to battle it. Water becomes contaminated in many different ways, including inadequate water systems, flooding, and a lack of proper sanitation. Most solutions (such as large filtration plants, new water systems, or a higher standard of living) are far too expensive or complicated for poor nations to implement. And because the problem exists primarily in poor countries, there seems to be little money to be made in fixing it, so most scientists concentrate on more appealing challenges.
In December 1992, an outbreak of a new and particularly dangerous strain of cholera began in southeastern India. Dubbed "Bengal cholera," within months it had spread throughout India and into neighboring countries, killing up to 10,000 people. The tragedy inspired Ashok Gadgil, an Indian-born scientist working at the Lawrence Berkeley National Laboratory in California, to look for a new way to purify drinking water. Using science no more complex than the ultraviolet light emitted by an unshielded fluorescent lamp, he built a simple, effective, and, most important, inexpensive water disinfection system. Dozens of these systems are now installed around the world, and many more will be in use soon.
Born in Bombay, India, in 1950, Gadgil was interested in science from a very early age. "I finished reading all the high school books on general science by the time I was in the fourth grade," he remembers. His parents indulged his interests by buying him chemistry and mechanics sets, books, and electrical components. "One great thing my parents did was bring home Popular Science and Popular Mechanics and Scientific American," Gadgil says. "So even though I was in Bombay, I had access to the kind of excitement that these magazines conveyed." Though Gadgil's parents wanted him to become a doctor, he thought it would be "extremely boring to be doing the same thing all your life." Instead, he chose to pursue physics. He received his bachelor's and master's degrees in physics in India and then, in 1973, came to the University of California at Berkeley to continue his studies.
At Berkeley, Gadgil explains, "Two things really struck me. One was the high level of affluence in the U.S. The second thing was getting a sense of how important it is to have science applied to address problems that are societally significant. . . . The basic science is well understood, but nobody had bothered to take the final step to convert that into a useful technology."
A Return to India
In 1983, Gadgil and his wife decided to return to their home country to try to give something back to their community. For the next five years, he worked with a fledgling research institution to address some basic problems in Indian society, such as how to best heat water and houses. In 1988, frustrated by the shortcomings of India's bureaucracy and its higher education system, he returned to Lawrence Berkeley Lab to work on problems of energy efficiency.
Gadgil remained involved with science back home, though, occasionally sending papers and other information to his colleagues there. One of India's problems that stayed in his mind was that of contaminated drinking water. There are three basic ways to kill bacteria and viruses in drinking water: chlorination, boiling, and ultraviolet light. Chlorination depends on large-scale treatment plants, and thus was impractical in a country with a poor water infrastructure. Boiling water requires an impractically large amount of fuel, even more than what is needed to cook food. Ultraviolet (UV) light seemed like a great alternative to these methods. A certain wavelength of UV light has a profound affect on bacteria and viruses. When used for a short period of timeabout 12 secondsUV light damages their DNA, preventing them from reproducing or even making the enzymes that keep them alive. They die soon after this exposure, and since they can't reproduce, even if live bacteria or viruses are ingested by a person, no illness will occur.
The Power of UV Light
During the summer of 1993, Gadgil and a graduate student investigated the effectiveness of UV light and whether it was economically feasible. "We were completely amazed," he says. "Using the simplest engineering, we could disinfect water for half a cent per ton. That's shockingly cheap. You could disinfect one person's drinking supply for a full year for a couple of cents."
From his experiences in India, Gadgil knew that any system would have to require little maintenance and not take for granted basic infrastructure like electricity and water pressure. The system he and his student built, later named UV Waterworks, is remarkably simple. In a compact, enclosed box, a UV lamp is suspended above a shallow pan. Water runs into the pan under the force of gravity, where it is exposed to the UV light, then into a holding tank. The only power that is needed is about 40 watts to power the light; this can come from a car battery. The system can disinfect four gallons of water a minute, killing 99.999 percent of bacteria and viruses. This produces enough clean water to serve more than 1,000 people.
Water Health International, the company founded to bring the technology to market, now makes several different versions of Gadgil's disinfection system, for small and large applications, for emergency use, and for locations that also need to filter out silt and other large contaminants. Prices start at about $1,500.
UV Waterworks systems have been used in India, South Africa, the Philippines, Honduras, and other countries. Since 1998, the Mexican government has installed about 100 in Guererro, a state on the Pacific in southwestern Mexico. The results have been very positive. In the summer of 2000, Gadgil reports, people from Water Health International returned with stories and data showing a dramatic decline in the incidence of diarrhea among children and adults. And preventing deaths and illness are just the most visible effects of purifying waterit also protects children from stunted physical and mental growth. "This is the kind of story that really makes my day, really makes me happy," Gadgil continues. "It makes me feel good when I get up in the morning."