The recipe I'm using is this: 4 cups hot tap water, 1 bar soap grated (I used Fels Naptha). 1 cup Arm and Hammer Super Washing Soda, 1 cup borax.
Grate soap and melt in 4 cups of hot water stirring continually over medium heat. Put 2 gallons of hot tap water into 5 gallon bucket, add melted soap, soda and borax. Stir until all is dissolved. Add enough water to make 4 gallons. Let set overnight and it will gel slightly. Stir before using. Use 3/4 cup for a large load of clothes. Has also been used for cleaning woodwork, porches, vinyl siding, etc. You can add 10-15 drops of essential oil if you want fragrance.