New Fears Raised Over Safety of D.C. Water

But the working group said the high levels found during the chlorine flushing reflect badly on what it calls the aqueduct's antiquated treatment system and the EPA's lack of knowledge about the ramifications of using a brew of chemicals to make dirty river water potable.

"It's time to face up to the fact that it's impossible to take the Potomac River in its current polluted state, put it through a very old, rudimentary treatment system and get water that people can safely drink," said the group's executive director, Richard Wiles.

His organization recommends that the U.S. Army Corps of Engineers, which operates the aqueduct, switch to carbon filtration to remove more chlorine byproducts and that residents use Brita-like filters until then.

Wiles said the District's water problem is a "classic case" of a national water-treatment problem.

Although the EPA has urged utilities to disinfect with chloramines instead of chlorine, many utilities find the chloramines are not strong enough to kill microbes throughout their vast distribution systems. They flush every year or two with chlorine to kill pathogens such as cryptosporidium, which can kill people with vulnerable immune systems. Some studies suggest chloramines are creating more toxic kinds of chlorine byproducts, few of which have been thoroughly studied.

"We switched from one treatment to the next" before knowing whether it was safe, Wiles said.

To carry out the tests, the working group submitted samples to an independent lab, Environmental Engineering and Technology. It tested for two disinfection byproducts: total trihalomethanes and haloacetic acids. Nineteen sites were tested, but one sample was lost.

The tests found that trihalomethanes were not markedly increased and did not exceed safety limits. But haloacetic acids were at the highest levels in the city since 2001, when the aqueduct started chloramine treatment.

The highest concentrations were found at a bathroom tap at the Martin Luther King Jr. Memorial Library, at an elementary school in Northwest Washington and at the home of a pregnant woman. Unsafe levels were also found at water fountains and bathroom taps at two public parks, in Anacostia and Fort Dupont, and at the National Zoo.

Robert Etris, director of public utilities for Falls Church, and David Hundelt, chief of water, sewer and streets for Arlington County, said they were not worried about the high levels.

"Well, if it were in my water system I would be, but we are not finding that in our system," Etris said of the chlorine pollutants. "If these samples were taken during the chlorine flush, which was a very short amount of time, then the numbers might be on the high side."

Hundelt agreed that the spike in levels should not make consumers fear for their health. "The risk is not an acute risk," he said.

Staff writer Amy Orndorff contributed to this report.