Pour ice cubes into the disposal and run the disposal with cold water from the tap. This will loosen any stuck food and help to sharpen the blades.
Fill the pot or tea kettle with 4 cups water and bring to a boil. Put the lemon quarters and baking soda into the disposal. Gently pour approximately 1 cup of the boiling water into the disposal and turn it on.
Pour the remaining hot water into the disposal while it is still running. The lemon, baking soda and hot water will help flush and freshen the disposal. Once all of the boiling water has been poured down the drain, continue running the disposal with cold tap water until the lemon and baking soda have been completely flushed through.