But that small bottle of expired pills your doctor prescribed a few years ago? That's a bit more difficult.
Efforts are under way to make it easier to properly dispose of unused medicine as more officials see pharmaceuticals as a potential threat to drinking water. But free take-back programs are still relatively scarce.
Some of the larger chain pharmacies, like Rite Aid and Walgreens locations, sell $3 envelopes that customers can use to send their medicine to a special disposal facility to be incinerated. Some hospital pharmacies will accept unused medicine, but many don't advertise the fact. And although some government agencies and police departments have collections - in New Jersey, the federal Drug Enforcement Agency took in 7 tons of prescription drugs in a take-back event in 2010 - many are held on just one or two days a year.
Although trace amounts of prescription drugs have been found in drinking water across the nation there is still debate among government agencies over exactly how medicine should be disposed.
The federal Food and Drug Administration recommends flushing more than two dozen drugs to reduce accidental use or illegal abuse. The state Department of Environmental Protection opposes flushing, but recommends throwing them out in the trash, which one water utility executive says just pushes the problem into the future.
In 2008, federal researchers found traces of heart medicine and the mood-stabilizing carbamazepine at the Passaic Valley Water Commission's drinking water treatment plant in New Jersey. The water, drawn from the Passaic River, also had caffeine, codeine and three other drugs.
No one knows how dangerous this is.
"The amount that constitutes a threat has not really been determined at this point," said Karen Fell, assistant director of water supply operations for the DEP. "It's not believed to be a threat, but this is an ongoing process. There are a lot of studies looking at this."
Researchers at water utilities are looking for way ways to filter pharmaceuticals from drinking water using membranes and carbon filters, but it's difficult. No single treatment can remove them all because of a wide array of chemical structures and properties, according to the American Water Works Association, a trade group for water utilities.
The best way to deal with the problem right now is to make sure drugs are properly disposed of so they don't have the chance to get into the water supply, said Rich Henning, a spokesman for United Water, which serves 800,000 people in Bergen and Hudson counties in New Jersey. The utility recently partnered with two of the area's pharmacies for a take-back program.
"This is a way to stop it before it becomes a bigger problem," Henning said.
Miller's Pharmacy in Wyckoff, N.J., began accepting unused medication about a year ago. It's caught on with customers. The drugstore has sent 12 large boxes to be incinerated, with the leftover ash buried at a hazardous waste landfill.
Owner David Miller expects to take in more now that President Obama signed a federal law that will allow pharmacies to collect controlled substances such as narcotics.
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