Bring 4 cups of water to a boil.
Pour 1 cup of washing soda into a large glass bowl then slowly stir in 2 cups of boiling water until washing soda is completely dissolved.
Stir in ½ cup Sal’s Suds until well combined. Then slowly stir in remaining 2 cups of boiling water.
Cool to room temperature, store in a glass bottle. Use ¼ cup liquid detergent per load.