Question:
New pollutants imperil water supply Just a few decades ago, it seemed the nation had won the war on bad water. Modern pipelines, chlorination and sewage treatment had all but wiped out virulent, waterborne plaguesis it right?

Answer: Today, water system operators are battling a host of new threats, from heartier bacteria to increasingly toxic industrial pollutants, pesticides and fertilizers.

"The margin for error is closing," says Dennis Juranek of the Centers for Disease Control and Prevention. "Water utilities are presented with sewage or industrial waste much more today than 20 years ago. Back then, an operator could forget to put in chlorine one day. If you did that now, there's a very good chance you'd have a (disease) outbreak."

Since 1974, the number of contaminants regulated by the Safe Drinking Water Act has grown from 13 to 83, ranging from dioxin, an industrial and agricultural byproduct, to such naturally occurring toxins as radon. System operators must do scores of water tests a year, yielding thousands of results.

The rules "resulted in improvements in water quality, and systems have done their best to deal with them," says Diane VanDe Hei, executive director of the Association of Metropolitan Water Agencies. "But there is a lot to do. There are a lot of technical challenges."