Fill a pot with 1 qt. water. Put it on the stovetop and bring it to a boil.
Take the pot off the stove and stir in 2 cups each of borax powder, grated Castile soap and washing soda. Stir well until all of the powder and soap has dissolved.
Allow the mixture to cool down for a couple of hours. Pour it into a 5-gallon bucket.
Add 2 gallons of water. Stir the mixture again.
Store the bucket of liquid soap in a large pail with a lid. Use about ½ cup per load of laundry.
Pour 16 cups baking soda into a bucket. Add 12 cups borax powder and 8 cups grated Castile soap.
Add 3 tbsp. lemon, lavender or grapefruit essential oil. Mix up the ingredients well with a whisk.
Store the powdered detergent in a container with a lid. Use about 1/8 cup for each load of laundry.