Soda, like vinegar, is a natural remedy for removing soap scum, bad odors and lime from your washing machine in a non-harmful way. But where do you add the soda? You can add the soda directly to the drum of your washing machine, or put it in the detergent drawer. If you add the soda to the detergent drawer, that part of your washing machine will also be cleaned and descaled immediately. A cup (or a big handful) of soda is basically enough for this. Then you can start a normal wash program at 60 degrees or warmer. 90 degrees is recommended. It is best to clean your washing machine in this way once a month.