Weekly Drain Maintenance:
Once a week, flush your drain by boiling a large pot of water. Pour one half of the pot down the drain. Wait 5 minutes and pour the rest down the drain.
Monthly Drain Maintenance:
Use an enzymatic cleaner once a month to keep your drains fresh and clean. My favorite is Bi-O-Kleen's Bacout Stain and Odor Eliminator. Using this, or another enzyme cleaner, once a month will help maintain your drain and keep odors out.
Drains With Disposals:
Running ice cubes and orange peels through a garbage disposal is a great way to knock of any residue on your disposal blades. To freshen a disposal drain put slices of citrus peels through the disposal. Make sure to slice the peels, because large peels can jam a disposal.
Seasonal Drain Maintenace:
2-3 times a year, flush the drain with baking soda and vinegar. Run hot water down the drain. Pour 1/2 cup of baking soda and 1/2 cup of vinegar with the hot water down the drain.