Oil that goes down the drain can clog pipes and pumps in public sewer lines or in wastewater treatment facilities, according to the Environmental Protection Agency. To dispose of used cooking oil and bacon grease responsibly, let it cool, pour it into a container, seal, and place in the trash. But in a perfect world, used cooking oil should be recycled. Check earth911.com or call your local municipality to see if there's a recycling facility near you. You can also ask local restaurants if they save and send old oil to be converted into biodiesel fuel and if they accept donations. For oil that will be recycled, filter food particles out with a strainer when the oil is cool, then store in a sealed container in the refrigerator until you've got plenty for collection.
According to the U.S. Department of Agriculture, you can also reuse oil or bacon grease for, say, frying eggs. (Both will keep in the refrigerator for a month if strained and tightly sealed.) With either oil or grease, remove the excess from pots and pans with a paper towel before washing.