You need a 5 gallon bucket.
4 cups hot tap water
1 grated bar of Fels-Naptha soap
1 cup Arm & Hammer Super Washing Soda (or a homemade substitute*)
½ cup Borax
Add the grated soap to the hot water and stir until dissolved. Mix in the soda and borax. Pour into a 5 gallon container and fill with warm water. Put a tight lid on and let it set over night. Fill your laundry containers half way with the solution, and then fill the rest of the way with water. Shake before use. I use about 1/2 cup per super-sized load.
I make 10 gallons at a time to save myself the preparation time.
Any time you are using 5 gallon buckets with liquid in them, you need to be cautious around babies and toddlers due to the drowning risk. Keep a lid on them.
*Homemade Washing Soda
I have been unsuccessful in my attempts to find washing soda near me. You can make your own washing soda at home by heating baking soda in the oven at 400° F for about 45 minutes. Store in a clearly labeled airtight container. When you heat the baking soda, you release the moisture and carbon dioxide which causes the chemical change needed to convert the baking soda (sodium bicarbonate) into washing soda (sodium carbonate). I was told it can convert back in humid climates, so the airtight container is necessary.
I remove any solids and blot moisture from the stain. Then I take the homemade laundry detergent and pour that onto the stain. Then I rub with a bar of Fels Naptha soap. Then, I sprinkle with Oxyclean. I let this work for a few minutes, and then I wash it. It works well on those ground in stains.
One of the most important rules you can follow when making your own products or medicines is LABEL EVERYTHING CLEARLY WITHOUT FAIL. It's a safety thing. Your family is worth that extra few minutes to grab a permanent marker and make a label. I write the recipe right on the bottle too.