~ UPDATE! ~
I have used this recipe for about a year and a half. While I have been happy with it's performance and for the dollars we have saved, a sad thing has happened. Our energy-efficient washer has been leaving yellowish stains on light colored clothes. The washer repair man has blamed the homemade detergent. If you have one of these new-fangled washers, please look up a recipe specifically for an energy-efficient model. For now, we are using Tide.
My neighbor, Sherry, tipped me off to do-it-yourself laundry detergent. I had never really thought about making THAT before. But after telling me all the benefits--no extra chemicals invading your family's linens and clothing, not to mention how much money you can save--I was sold (at least to give it a try!).
This recipe comes from The Family Homestead website:
1/2 bar Fels Naptha soap or 1 full bar Ivory soap, grated
1 cup washing soda (note: this is not the same as baking soda!)
1 cup borax powder
small (2-gallon) bucket
container(s) to hold your finished soap (I used two recycled containers of store-bought detergent)
Heat grated soap and 6 cups of water in saucepan until soap melts. Add washing soda and borax. Stir until dissolved. Remove from heat. Pour 4 cups hot water into bucket; then add soap mixture and stir. Next, add 1 gallon plus 6 cups of water and stir. Let sit for 24 hours. It will gel up. Use 1/2 cup per load.
These supplies initially cost me under $14 total from Rural King. They will last for several batches! Pretty good, I'd say, compared to $11 for one large container of detergent from the grocery store. Because it's gentle, it's still essential to treat stains as normal, and add Oxyclean (or whatever you usually use) for tough loads. I've made two batches in this new year, and plan to continue. And a bonus? It makes your house smell nice and clean!