There are a whole bunch of laundry detergent recipes here at TipNut
I’ll be using the following from Suzanne McMinn's Chickens in the Road
I'll be using Fels Naptha soap for the first batch and see if I break out in hives or any other strange skin anomalies. If I get all red and bumpy, I'll use a castille soap instead.
How to make Homemade Laundry Soap:
1 regular (not large bath-size) bar of plain soap
1 cup Borax
1/2 cup washing soda
1/2 cup baking soda
Grate the soap. (Soap grates easily.)
Heat 3 pints (6 cups) of water on the stove and add the grated soap. Stir occasionally, until the soap melts.
I use a pint jar and a quart jar for all the water measuring for this recipe as it’s faster than doing it one cup at a time.
Once the grated soap is melted, add 1 cup Borax, 1/2 cup washing soda, and 1/2 cup baking soda, stirring to dissolve.
I use a large pot, large enough to hold all the water I’ll need for my mixture so I don’t have to get a separate pail. If your pot isn’t large enough to hold over two gallons, you’ll have to transfer the mixture to a bucket at this point.
Add one quart jar of very hot water to your soap mixture.
Stir well. Add six more quarts of cold water. (If you’d like to add some scent, now is the time. Add 10-15 drops. I don’t add scent–it’s no big deal to me and would increase the cost. I’m happy with my laundry simply smelling fresh.) Stir well again and ladle or scoop the mixture into your container(s). I’ve found that three large plastic coffee containers are exactly right to hold this recipe. They come with handy snap-on lids and one is just right to keep by the washer for daily use.
Use 1/2 cup per large load of laundry. Mixture may gel or clump as it sits, so stir before each use. (I keep a 1/2 cup scoop–in a plastic bowl to prevent mess–on top of my washer to measure out the detergent. I just stir it with the scoop before measuring it out.)