Chlorine out, ozone in as water purifier Los Angeles Herald Examiner Tuesday, December 13, 1988 By Emilla Askari Of all the deadly technologies developed during World War 1, none was more gruesome, none more cruel than poisonous chlorine gas. One strong whiff and a soldier would start coughing blood. The tortured hacking could go on for days, inevitably, the gas would kill -- hundreds of thousands of young men. In farmhouses and hospitals throughout Europe, people watched. And when the War To End All Wars was done, they gagged at the thought of disinfecting their drinking water with chlorine. Not so across the Atlantic. In America, hundreds of water systems began disinfecting their water with chlorine in the 1920s and '30s. To this day, it is a commonplace chemical that we drink every day, rub from our eyes after staying too long in the pool and use to kill bugs in the water as a matter of course. Soon, however, this will all change. American technology has finally confirmed what the Europeans suspected all along: Adding chlorine to drinking water is not a healthy practice. When chlorine combines with the byproducts of rotting leaves, a family of chemicals called trihalomethanes, or THMs, are formed. THMs are carcinogenic. One study by the President's Council on Environmental Quality found that people drinking chlorinated water had a 13 percent to 93 percent greater chance of developing rectal cancer and a 53 percent greater chance of getting colon cancer than people who drank untreated water. For years, no one knew that people were getting small doses of THMs every time they brushed their teeth or made lemonade. It wasn't until the mid-1970s that the Environmental Protection Agency's water quality lab in Cincinnati first isolated THMs in drinking water. Before that, "We didn't worry about these cancer-causing chemicals because we didn't know they were there," said Pete Rogers, chief of the California Department of Health Services' drinking water branch. "We didn't know how to measure them, and we didn't really know what the long-term effects (of drinking them) were." All that is much clearer now. At the current maximum contaminant level of 100 parts of THM per billion parts of water, the EPA estimates that one additional cancer will strike among 100,000 people who drink two liters of water a day for 70 years. The EPA takes fewer risks with other drinking water contaminants. For example, its recommended level for the industrial solvent trichloroethene, or TCE, is five times stricter when measured by the number of projected cancer deaths. The reason the EPA went easy on THMs: If the standard had been any tougher, water agencies wouldn't have been able to meet it unless they stopped chlorinating. And there was no alternative. Not in this country, not in 1979, when the standard was set. As it was, the water industry balked at having to meet even the lenient 100 parts per billion standard for THMs. The first reaction of the American Waterworks Association, an industry group, was to file a suit attempting to block the standard's implementation. Too hard to meet, the association claimed, especially for agencies that get a lot of their water from rivers and streams, which are heavily laced with THMs' chemical "precursors." Well water, in contrast, doesn't contain THM precursors; it never comes in contact with decaying leaves. Eventually, the suit was settled when the EPA granted variances from the THM standard for some agencies that had a particularly hard time complying. Next year, however, the EPA says it's really going to get tough. It plans to lower the maximum allowable level of THMs to between 50 and 10 parts per billion. Again, water agencies are balking. This time, however, they also are scrambling to find an other method of disinfecting water. One possibility that has been used for years in Europe: ozone. The gas, which smells like watermelons, disinfects as well as chlorine does. It is more expensive. Europeans pay much more for their water than Americans. But, unlike chlorine, ozone disappears into the air within 24 hours, leaving behind no toxic residuals -- as far as researchers can tell so far. "The fact of the matter is that our analysis of drinking water is incomplete," said William Glaze, a professor at UCLA's School of Public Health who specializes in water treatment. "We're still finding things we didn't know were there." For more than a year, Glaze has been focusing his microscope on water samples from the city of Los Angeles' new filtration plant in Sylmar. The 2-year-old, $106 million plant is one of the largest in the world that disinfects with ozone. So far, Glaze says he has found nothing alarming in the product of the plant he calls "one of the best in the world." There, where the Los Angeles Aqueduct dumps its relatively pure load of runoff from the Owens Valley, man-made lighting bolts pass through thousands of glass tubes in the plant's huge ozone generators. Inside the tubes, the electricity converts liquid oxygen into ozone. The gas is then piped over to holding tanks the size of small auditoriums. The tanks are filled with water and the ozone is allowed to percolate through it. A thick porthole allows visitors to peek inside the cement tanks and watch the ozone bubble away like champagne. From Egypt, Japan and Monroe, Mich., water managers have come to observe. Some visitors also have come across town, from the mighty Metropolitan Water District of Southern California. MWD, the state's largest water wholesaler, already has converted its treatment plants from chlorine to chloramine, a combination of chlorine and ammonia that's less likely to combine with the THM precursors. But MWD gets all of its water from rivers: the Colorado to the east and the Sacramento to the north. These sources are high in decomposing leaves, and thus in THM precursors. When the new EPA standards come out, MWD is going to have to do even more to reduce THMs. The agency -- which supplies half the water used by coastal Southern California -- is studying the possibility of converting all five of its treatment plants to a combination of ozone and peroxide. The estimate cost: $150 million. At that price, MWD is fervently hoping that future research doesn't uncover any ozone byproducts as unhealthy as chlorine's. "If there are problems with ozone," said MWD water quality director Michael McGuire, "we're in a hell of a mess."