BLACKSBURG -- Jerry Higgins was stunned last year when he found out the water he was sending to 65,000 customers of the Blacksburg Christiansburg VPI Water Authority contained high levels of an acid that has been linked to cancer.

"We worked so hard and were so ahead of the ball game. Then we got hit with that," Higgins said.

Haloacetic acids, or HAAs, worried water providers up and down the East Coast in the summer of 2004.

The spikes were temporary, but they caused the U.S. Environmental Protection Agency to institute stricter rules for what can end up in water glasses and baby bottles.

And that in turn has prompted the authority, which serves most Montgomery County residents, to change the way it disinfects drinking water. On Monday, a new process called chloramination will go into effect.

But chloramination comes with its own risks.

Washington, D.C., switched to chloramination in 2000 and two years later a Virginia Tech scientist investigating widespread plumbing failures in homes also found high lead levels in the water.

Last month, two young boys in Greenville, N.C., were diagnosed with lead poisoning two years after the city switched to chloramination. In one of the boys' homes, health inspectors found pieces of lead solder in the taps.

Some experts theorize that chloraminated water may have corroded plumbing and caused the lead problems.

Lead is a toxic metal found in plumbing materials and old house paints that also occurs naturally in soil and water. Young children can suffer developmental delays and other health problems after prolonged exposure. Lead may also contribute to heart disease and cancer in adults.

Despite problems in D.C. and North Carolina, many water works around the country have used chloramination for decades without any noticeable lead problems.

Richmond has chloraminated its drinking water since 1960, and most of the water systems in Tidewater switched to the method in the 1990s.

Regular testing done across the state by the Virginia Department of Health has so far found no ongoing lead problems anywhere, Kelly Labonav, a spokeswoman for the department, said.

Chloramination is not that different from chlorination, the method the Blacksburg Christiansburg VPI authority has used for years to disinfect water. The new process simply adds ammonia to the chlorine, which forms compounds called chloramines.

The chloramines create fewer toxic by-products than chlorine. And they remain in the water longer, which discourages bacteria from growing in storage tanks and seldom-used plumbing.

The problem with chloramination, according to Marc Edwards, the Tech scientist who worked on the D.C. case, is that nobody really knows what caused the problems in D.C. and North Carolina.

Nor has anyone designed a foolproof test to determine if a water system that plans to switch to chloramination will be prone to lead-leaching.

"We have theories but no scientific basis for them yet," Edwards said.

To head off any problems with the local conversion to chloramination, Higgins hired Edwards to work on the project.

"You've got to make sure you don't have those situations," Higgins said.

The only way to do that is to test the water system for problems.

For the past four months, that's what Edwards has done. And the testing will continue for some time.

This kind of monitoring program "has not been done anywhere else to catch problems before anyone gets sick," Edwards said.

He believes other water works across the country will likely look to the Blacksburg Christiansburg VPI authority as a model.

And that model is important because experts estimate that more than half the water providers in the country will switch to chloramination in the coming years.