St. Louis Mayor Francis Slay examines a glass of water at City Hall in St. Louis on June 26, 2007. The U.S. Conference of Mayors voted St. Louis has the best-tasting city water in the country. St. Louis beat out 90 cities to win the $15,000 prize. (UPI Photo/Bill Greenblatt)

The announcement Thursday came on the heels of a Chicago Tribune report that found trace amounts of prescription drugs and other chemicals in local drinking water, the newspaper reported.

The Tribune, which hired an independent lab to test tap water, found very small amounts of a prescription anti-seizure drug, a common painkiller, a nicotine byproduct, caffeine and two chemicals used to make Teflon and Scotchgard.

Following publication of the story, Water Department Commissioner John Spatz said the city decided last month to conduct its own studies.

"This is an important environmental issue that has been brought to light," Spatz said. "We should be monitoring and making sure it isn't getting in the water. And we need the health agencies to figure out if there is anything to be worried about."