Add the baking soda and citric acid to a bowl and mix together with your hands. Add about 20 drops of essential oils, mixing that in with your hands as well.
Dilute the castile soap by adding one part soap to four parts water inside the spray bottle. Spray the solution lightly onto the top of the powder mixture, mixing it in quickly with your hands as you spritz.
Continue to spray the solution and mix it in until the powder mixture packs together easily in your hands like a snowball.Be careful not to spray too much liquid or the mixture will begin to fizz.
Roll the mixture into teaspoon-sized balls in your hands. Lay the balls out on a piece of parchment paper and allow them to dry until they feel firm. This will take up to 24 hours.
Store them in a glass jar and pop one out when you need to refresh your bath, sink, or toilet. Simply toss one down the drain with a little water or into the toilet bowl and watch as it fizzes away, leaving the drain or toilet clean and fresh smelling.