I learned how to make laundry detergent a few years ago. This all came about because:
1). I have a pathological need to try everything I read about on the internet that involves making things that most people purchase.
2). This saves money. Seriously. This detergent costs pennies per load.
3). It cleans just as well as the storebought stuff.
People used to do laundry with bar soap (often homemade) before the advent of powdered detergent. Then liquid detergents came along and the rest is history.
Want to make your own? Here’s how.
You’ll need:
2 (1 gallon) milk jugs (or a large empty detergent jug)
1 bar Fels Naptha or any other bar soap
1/2 cup borax powder
1/2 cup washing soda (washing soda, NOT baking soda)
Fill a pot with about 4 cups of water. Grate in 1/3 bar Fels Naptha, or 2/3 bar regular soap. Heat until the soap is melted, try not to bring the water to a boil.
Fill your milk jugs almost full with hot water – the 4 cups of water/melted soap will be divided between the jugs, so leave enough room in each jug for an additional 2 cups of liquid. (This is not an exact science. Estimation is fine. It will not blow up or turn into an alien if you don’t use exact measurements.)
Divide the soapy water evenly between the 2 jugs. Divide the borax and washing soda between each. Tightly cap each and shake to dissolve the powders.
Let sit at room temperature overnight and that’s it. You are ready to rumble, my friend. If your soap gels too much and comes out in big blobs, that means too much soap was added. Just shake the jug to break up the blobs and use as usual. Use the same amount of this stuff as you would storebought.
By the way, white vinegar is an amazing fabric softener. And you’re clothes will not come out smelling like a pickle, I promise.
Have fun!
Black Spruce Hound 
This is the most common recipe for homemade detergent but I caution those who use a septic tank system with the washer water going to it. Borax kills germs – good and bad. Over time the borax can overtake the good bacteria in the septic system and cause it to die which then stops the normal operation of the septic system. Baking soda and vinegar are also great for washing your laundry.
Vinegar is also a natural anti-bacterial so would not be better for septic systems if this were true. However, I cannot find anyone who states Borax is harmful to septic tanks.
On a quick Google search, I can't find any solid info that says borax is bad for a septic system. On the 20 Mule Team Borax site, they claim it's perfectly safe for septic systems. But you bring up a good point – if anyone is at all concerned about putting borax into their septic system, it's a good idea to remove the borax from the recipe and substitute it with baking soda or extra washing soda.
Love the recipe. Even if I don't ever get around to making it, the tip on the vinegar was awesome! It seems I am always running out of Downy, plus the stuff always gums up the washer. I am going to try adding white vinegar to my rinse this evening! Woo Hoo!!Thanks for sharing at SCC!Jennythelavendermagnolia
Jenny – thanks for checking it out!
Washing soda=sodium carbonate. Baking soda=sodium bicarbonate. Bake the sodium BIcarbonate at 4oo for a few minutes and you have washing soda. Borax is not the evil folks seem to think, but if it is a concern, pour a beer down the toilet once a month. That will help much the same way a probiotic helps a human-and if you have beer that is going to go stale anyway, it's a bonus.
I love homemade washing detergent. I use the super washing soda and borax, but instead of grating up Fels, you can use dish soap like Dawn, Great Value, or Ajax. Four to six teaspoons of dish soap mixed in per gallon has never made my washer explode in a mass of bubbles — if anyone is worried. Just putting that option out there to save a few minutes 😉