In the works for more than a decade, the move is designed to meet new Environmental Protection Agency water quality standards limiting disinfectant byproducts, some of which are potentially toxic.
Experts say chloramine has less of a chemical odor and taste than chlorine does, meaning the city’s tap water should appear purer to the senses.
“I think it’s a very good approach,” said Mel Suffet, professor of environmental chemistry at the UCLA School of Public Health. “It’s good for disinfection, good for odor, and good for byproduct control.”
Around April 1, the DWP converted Downtown L.A. and Hollywood onto chloramine. South and West L.A. were converted earlier this year. San Pedro, Tujunga and East L.A. have been on chloramine for years, if not decades.
The next phase is the San Fernando Valley, which officials expect to convert in the beginning of May. Before the DWP can switch over the Valley, it needs to get a state permit for a related ultraviolet treatment plant.
As water science evolved in recent years, regulators tightened the level of byproducts considered safe. Chlorine reacts with leaves, dirt and other organic material that falls into the water supply, producing some risky chemicals. Chloramine — a mix of chlorine and ammonia — has similar byproducts, but at only about 5 percent the level of those generated by chlorine, the EPA says. It also disinfects longer than chlorine, experts say.
The chloramine does directly affect some groups, though, so DWP officials sent letters warning people and businesses that chloramine can be toxic for both kidney dialysis patients and for fish. But with filters or treatment, it is harmless, officials say. Affected dialysis centers have been notified, said Albert Gastelum, DWP director of water quality.
Marc Grover, co-owner of Underwater Depot in Sherman Oaks, has been warning customers they need to buy certain solutions to treat their fish tanks. Some fish owners, he said, haven’t noticed the DWP fliers or letters, which came with their billing statements.
“People see stuff from the DWP and don’t read it,” he said. “We’ve been telling all our customers which products neutralize chlorine and chloramine. They’re completely different.”
For drinking water, the DWP’s latest water quality tests meet federal levels for the byproducts trihalomethane, haloacetic acids and bromate, said Bruce Macler, the EPA’s southwest region drinking water program toxicologist.
“They’re in compliance, so whatever they’re doing is working,” he said.
The DWP has built a UV plant, eight ammonia facilities, circulation systems and other components for a total cost of $300 million.
Los Angeles joins the Metropolitan Water District and many other water purveyors in making the switch to chloramine. Beverly Hills, Santa Monica, San Francisco and San Diego all use chloramine water. About half of U.S. utilities treat with chloramine, serving about 100 million people, Macler said.
When the MWD converted in the 1980s, it had to switch back temporarily to chlorine, and some people complained about the taste, said Mike McGuire, the former director of water quality at the MWD.
But today, “I don’t know if people have noticed much,” said Martin Adams, the DWP director of water operations. “People don’t usually call if there’s something good.”
The change at the DWP has been a long time coming. In 2002, the department decided to make the switch, according to its Website, and it has been slowly transitioning neighborhoods since then.
“The transition is very deliberate and very careful,” Adams said.
So careful that deadlines have come and gone. Regulators gave DWP a two-year extension for its latest projects, said Macler from the EPA, because “It was just so complex for them to figure out the engineering.”
The revised deadline was March 31, he said, and some of the transition has dragged beyond that date.
Regulations on byproducts have been updated occasionally since 1998, Macler said.
“We just keeping upping the ante,” Macler said. “Most of the byproducts are benign or of little consequence, where your body doesn’t have a problem.”
But some of the chemicals could be toxic to the liver or damage the nervous system, he said. Others have caused cancer in high doses during animal lab tests, he added, and “we do worry if it’s carcinogenic at high dose, what the impact is at the low dose.”
By, Mike Reicher