Still, Woods Cross shut down one of its four drinking water sources, which supplied half the city, due to contamination by tetrachloroethylene, which the EPA said consistently was above the Cancer Risk Screening Concentration. Karla Scott can see the well from her home, where someone representing Woods Cross showed up about five years ago asking to test her water.

"He said it was OK," Scott said. "You just go on with your life and don't worry about it."

If she wanted to, Scott could take a water sample for testing to the Utah State Health Lab, which sometimes takes special individual cases on, or to the private Chemtech-Ford Laboratories in Murray. The state lab does rigorous testing for water utilities throughout Utah.

Anderson said a test in 2004 showed that one of the three remaining active wells in Woods Cross turned up traces of trichloroethylene (TCE), but not at a level unacceptable by federal standards.

Bousfield said that in a few past isolated cases elsewhere in Utah, contamination has been so bad in drinking water supplies that people could actually smell chemicals in the water. When that happens, he added, there is a potential for an immediate health risk.

"It's such a rare occurrence," he said, unable to come up with a specific example over the phone. "I'm sure they do exist."

5th South Plume

One of two large plumes of polluted groundwater in the Bountiful and Woods Cross areas, defining one Superfund site, is bad enough that seven of 26 domestic wells in the affected area are believed to have been contaminated by chemicals at concentrations that exceed acceptable federal levels. The potentially cancer-causing chemicals connected to that site are perchloroethylene (PCE) and TCE.

The EPA calls those two plumes the Bountiful/Woods Cross 5th South PCE Superfund Site, a place the EPA has assessed as "Human Exposure Not Under Control." Mario Robles, the EPA's project manager over the 5th South site, federally listed as a priority in 2001, said last week that cleanup of those plumes migrating under about 450 acres could take about 15 years.

"Really, nobody knows — it could be more, it could be less," Robles said on the phone regarding a remediation time line.

So far, the plume contaminated with PCE has made its way into two residential drinking water wells, with one homeowner accepting the EPA's offer of being hooked up to municipal water without charge. The other homeowner, Robles said, is opting to rely on filters for clean drinking water, preferring its taste over city supplies.

"The issue is if they change it often enough," Robles said about the filter. "We explained the risks to them."

The remaining five of the seven affected domestic wells are used primarily for irrigation, and Robles said there is not a risk of human exposure to the polluted groundwater around those wells. State regulators don't keep track of water quality in private wells.