DIY Disposal Cleaner - 1/2 cup lemon juice & 1/2 cup baking soda Heat lemon juice in microwave for 30 seconds. Add baking soda slowly (it will bubble) and mix well. Turn on the disposal and pour down the drain. Turn on hot water for a few seconds to rinse away any mix remaining in the sink or the bowl. Use weekly. If disposal still has a bad odor, repeat.