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

Story by Peter Eisler. USA TODAY.

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 plagues.

But the truth has proven more complicated -- and elusive. Providing Americans with clear drinking water is getting tougher every year.

Sources of Water Pollution

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 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.

Sometimes, even the most rigorous efforts to combat contamination can''t do the job.

In 1992, Des Moines'' water works spent $4 million to install the world''s largest system for removing nitrates, which are components of fertilizers and manure that plague many agricultural areas and carry serious risks for infants and pregnant women.

Waste Water Pipe

Yet this spring (1998), the city warned that its tap water still was likely to exceed the legal nitrate limits because farmers used so much fertilizer during the 1997 drought. But unusually heavy rains ended up diluting contamination enough to keep the levels in check. But the city is now spending another $30,000 to upgrade its high-tech treatment system to handle growing nitrate threats.

Water systems face similar challenges in some of the new, hard-to-kill bacteria that crop up with growing frequency.

The struggle to control cryptosporidium and other bacteria has become even more complicated now that it''s known that increasing chlorine levels poses its own problems.

Studies now show that high chlorine concentrations can react with acids in water to create trihalomethanes -- compounds linked to spontaneous miscarriages and various cancers. In response, the Environmental Protection Agency is proposing new rules limiting THMs and other possibly dangerous "disinfection byproducts" in drinking water.

Grappling with new contaminants and legal standards forces water systems to "strike a really fine balance", says Jeffery Griffiths of Tufts University''s School of Medicine. "When you''re dealing with things like cryptosporidium on the one hand and spontaneous miscarriages on the other...there are no easy answers."