What you'll need:
1 cup washing soda (I use Arm & Hammer)
1/2 cup borax (I use 20 Mule Team)
1 bar soap (I use whatever’s cheap)
Approximately 3 gallons water
1 Large Container ( 5 gallon paint bucket w/ lid works)
1 Large pot for boiling
1 grater or kniffe to cut soap. I'd go with a cheese grater.
What to do:
put about four cups of water into the pan and put it on the stove on high until it’s at boiling, then lower the heat until it’s simmering.
While it’s heating up, take a bar of soap and cut it up into little bits. Slowly add the soap bits to the boiling water. Stir until dissolved.
Next get our your Large container and add 3 gallons of warm tap water. To this bucket add a cup of the washing soda and the soap solution you made and stir. Optional 1/2 cup Borax. Let sit for 24 hours with lid on.
Your finished soap should be a slimy soap/water mixture. If the water and soap separate thats ok just stir it a bit. If there's little soap clumps in the mixture that's ok too.
Use 1 cup per wash load and it will get you 52 wash loads.
Now you'll wonder, how much would I be saving for all this work and is it worth it. The answer is yes! Here's the breakdown for ya:
The supplies will run you about $10 give or take a dollar. With your supplies you should make atleast 4 buckets worth of soap. So at 52 x 4 = 208 loads for $10. I'd say that's a few dollars cheaper than tide. In short, nine loads using my homemade detergent has the same detergent cost as one load of Tide with Bleach Alternative.