How safe is the water?

Researchers have found that exposing it to ultraviolet light at treatment plants or bringing the water to a rolling boil for one minute seems to be effective. The EPA's proposed rule should be published in its final form this summer, Mr. King says.

But the list of emerging pollutants continues to grow as scientists conduct new tests. The US Geological Survey (USGS) released a study in 2002 on 95 organic contaminants such as prescription drugs and detergent byproducts that it looked for in US surface waters. The group tested 139 streams located downstream from major cities or animal feeding operations in 30 states and found 82 of the 95 chemicals on its list. No drinking-water standards or health-advisory requirements exist for many of the chemicals, whose effects have yet to be studied fully. The USGS will repeat and expand the study next year, and it hopes to release an updated report in early 2007, says Herb Buxton, coordinator of the USGS toxic substance hydrology program.

The USGS already has a list of more than 130 emerging contaminants that Mr. Buxton considers "sentinels" of potential environmental and human health effects. For example, Fluoxetine (Prozac), which has been found in waters in Britain and the US, can delay the development of fish. And substances that are thought to interfere with the body's hormone system and hinder fertility, known as endocrine disruptors, were found in treated wastewater and municipal drinking water in Atlanta in 1999.

"Finding these contaminants from households, animal agriculture, and industry makes us realize that the chemicals we use, even in very small amounts, can be concentrated in our wastewater and then deposited in streams that in turn are water resources," Buxton says.

While the effect of small amounts of pharmaceuticals, including antibiotics and antidepressants, in the water remains unknown, one researcher believes it could be relatively easy to remove some of them from drinking water with existing technologies. Water treatment operators could cut trace levels of drugs that get through sewage treatment systems by adjusting the amounts of activated charcoal and chlorine used to purify water now, says Craig Adams, a professor of environmental engineering at the University of Missouri-Rolla. Simply increasing the amount of activated charcoal can remove up to 90 percent of the drugs, he says.

The AWWA's Roberson says there is no magic bullet for drinking water contaminants. Thousands of potential contaminants are in the water, but the EPA has established drinking-water standards for only about 90 of them. The EPA is continuing to examine newly discovered pollutants to see if they need to be regulated. Local utilities also are required to test their water, usually once every three months, and every July they are required to send a water-quality report to homeowners. The reports are posted on the EPA's website (www.epa.gov/safewater/dwinfo.htm).

"Most people just throw the report away, but it can be incredibly useful," says Helen Rogan, executive editor at Organic Style magazine, which surveyed five contaminants in the water of 25 cities this past fall. She suggests that consumers who want to feel secure about their drinking water read the utility company's water report, have their tap water tested, and keep the EPA's Safe Drinking Water Hotline number handy (800-426-4791). The hotline also can suggest solutions (a filter, for example) if local water fails to meet federal standards.

"Your tap water is safe unless you have reason to believe otherwise," Ms. Rogan adds. "And if there is something wrong, you'll find out pretty fast."

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