You cannot taste them. You cannot see them. But scientists say they are there: traces of prescription drugs in the water that comes from many people's faucets.

"Everything from antidepressants to heart medication to birth control pills to caffeine" has been found in certain drinking water, said Dr. Brian Buckley, environmental scientist at Rutgers University in New Jersey.

In his lab in New Brunswick alone, Buckley has found acne medication, barbiturates, caffeine and birth control medication in the water system.

While most of the medicines we take are absorbed by our bodies, he said, traces do escape via human waste and are flushed into our treatment plants, winding up in the water supply.

While the long-term health risks are unclear, there is evidence that medicines in the water, as well as hormones and chemicals, have negatively affected frogs and fish.

"The concern is we don't know what these chemicals do in the body over a lifetime of exposure," Buckley said.