Pure soap is not recommended for use on laundry due to the fact that soaps can leave a residue on your diapers and covers, in the form of soap scum. This makes the diapers repel moisture rather than absorb it, and it is also harsh on the laminates used in your diaper covers, making them absorb rather than repel liquid. Soap and detergent are both cleaning agents, yet detergents are formulated specifically for laundry and other purposes. A detergent is a synthetic product, meaning the ingredients are processed and mixed together to form the detergent. Soap is made by simply mixing lye with vegetable or animal fats, although other ingredients may be added. The best choice for washing your diapers is to use detergent on them; however, all detergents are not alike! For cloth diapers, you will want to choose a detergent with no additives such as Brighteners, Chlorine Bleach, Enzymes, Dyes, Fabric Softeners, and Fragrance. Check out the Diaper Jungle website to see which detergents contain these additives. These ingredients can be harmful to your diapering products, your baby’s skin, and/or the environment. The only detergent we recommend with 100% confidence that it is safe for your diapers, your baby, and the planet we share is our very own. True, Thirsties Pre-Wash and Super Wash can be more costly than store brands, but will keep your diapers clean and looking like new longer! For other recommended detergents, please go to our FAQs page on our website: http://www.thirstiesbaby.com/customer-center/faqs/ -> Laundering Tips.