It cost approximately $5.50 for the ingredients and lasts a two person family well over a year. Saving us around $100. I was skeptical at first, but now am a total convert.
*A bar of Fels-Naptha (found in the detergent aisle) $.97
*Arm & Hammer Super Washing Soda (found in detergent aisle) $2.45
*Borax (I used 20 mule team) $1.99
*Bucket (5 gallon or you can get a large mop bucket at the dollar store)
*Three gallons of water
1) Grate the bar of soap with a regular cheese grater. I preheat two gallons of water in pots on the stove, since I don't have a large enough pot for that I split the recipe and have two one gallon pots going. Add the soap curls evenly to the water, add 1 total cup washing soda, and 1 total cup borax. Heat the solution until all of the curls are melted, the water will turn a yellow color due to the coloration of the bar.
2) Stir occasionally as the soap curls melt. Add essential oils if you'd like. I usually add a combination of lavender, orange and lemon! Sounds like a weird combo but it smells delightful. While you are waiting fill the bucket with one gallon of room temperature water. After the curls are completely melted, add the detergent to the water in the bucket, pour slowly, and mix well.