New Treatment for San Francisco Water System

January 23, 2003

Change is coming to the water delivered by San Francisco's Hetch Hetchy system, but most who drink that spark-ling Sierra snowmelt will barely notice.

Starting in November, the San Francisco Public Utility System will switch disinfectants, going from chlorine to a chemical mix of chlorine and ammonia known as chloramine, the district announced Tuesday.

The conversion is part of a nationwide trend and is aimed at meeting future water regulations, reports Douglas Fischer of The Daily Review. Chloramine lasts longer in the water and produces fewer harmful byproducts, according to the water district and the U.S. Environmental Protection Agency

"The chloramine conversion project strengthens our efforts to provide the highest quality drinking water to our customers," said SFPUC general manager Patricia E. Martel. "The conversion … will help us meet new and future water quality regulations, enhance water quality and we anticipate that it will improve taste and odor as well."

In the Bay Area, most other water districts have already made the switch, including the Alameda County Water District, the East Bay Municipal Utilities District, the Contra Costa Water District and the Marin Municipal Water District.

The switch should be virtually unnoticed, water officials said Tuesday. If anything, Hetch Hetchy water should end up tasting a little better, as chloramine is tasteless and odorless and has none of that peculiar chlorine smell.

The Hetch Hetchy system delivers water to 2.4 million customers in San Francisco, San Mateo, Santa Clara and Alameda counties. Hayward gets all its water from Hetch Hetchy pipes, while the cities of Fremont, Union City and Newark get about 30 percent of their supplies from the system. Almost every town in San Mateo County draws from the SFPUC network.

Across the country, water districts have discovered chloramine is more effective than chlorine alone because it produces lower levels of disinfection byproducts such as trihalomethanes, suspected carcinogens that form when chlorine mixes with natural compounds found in water – particularly water that's already been through a sewage treatment plant.

With Hetch Hetchy drawing water from a reservoir in Yosemite National Park, that hasn't been a concern … until now, Brown said. "We've consistently (met) the regulations for a number of years, but the regulations got stricter."

The conversion effort will require construction of three treatment facilities – including one in the Sunol Valley and another in San Bruno – and modification of various other facilities along the Hetch Hetchy system.

A 10,000-square-foot dechloramination facility and a 2,000-foot long underground pipeline are being built at the Pulgas Water Temple site near Woodside.

The switch will prompt only minor changes from municipalities accustomed to dealing with chlorine-treated water.

"You have to watch the age of the water," said Burlingame public works superintendent Phil Scott, who added that a simple change to the city's pipe-flushing schedule should solve that problem.

"One of our biggest efforts is just the outreach," he added. "The average homeowner probably won't notice."

Source:

The Daily Review

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