The problem of pharmaceutical residue turning up in water supplies is one we've written about before. It's a serious and growing problem, and right now, no one really knows what health risks the public might face from exposure to drugs in drinking water.

In 2008, the Associated Press published the results of its own five-month long investigation into drug residues in public water supplies. The probe revealed that 46 million Americans were being exposed to pharmaceutical ingredients via drinking water. The Associated Press also found that many y communities do not test for drugs in drinking water and those that do often fail to tell customers they have found medications, including antibiotics, anti-convulsants, mood stabilizers, and sex hormones.

At that time, such drugs were found in drinking water supplies in 24 major metropolitan areas. The report pointed out that water providers are not required to test for pharmaceuticals and the Environmental Protection Agency's (EPA) budget for the testing of endocrine disruptors in America's waterways had been cut by 35 percent.

The Associated Press investigation prompted federal and local legislative hearings, brought about calls for mandatory testing and disclosure, and led officials in at least 27 additional metropolitan areas to analyze their drinking water. Following the reports publication, positive tests were reported in 17 cases in locations that include Reno, Nevada; Savannah, Georgia; Colorado Springs, Colorado; and Huntsville, Alabama.

Most drug residues end up in municipal water supplies through normal bodily functions. But some end up there because people often dispose of unused medications by flushing them down the toilet. According to an article on, most government organizations now recommend that you dispose of old medications in the trash, rather than the toilet. In 2007, the Office of National Drug Control Policy, the EPA, and the Department of Health and Human Services issued the first set of federal guidelines for proper disposal of prescription drugs. According to, these guidelines recommend taking unused medications out of their original packaging, mixing them with other items in the trash that are "undesirable" (for instance, used cat litter), placing the concoction in a zip lock bag, and throwing it in the trash.

The article does point out that there are a few drugs, such as certain narcotics, that the guidelines say should still be flushed. A list of those medications can be found here. Also, the guidelines aren't binding, and state and local authorities may mandate different procedures.

Finally, the report said consumers may want to utilize "take back" programs that are popping up now. Generally, these programs involve turning in unused medications to a pharmacy or other organization for disposal. Also, there may be opportunities to donate unused medications to charity, depending on state laws.