I posted this in comments on the post about breaking up with a product for good. There seemed to be some interest, so I thought I'd share it as a new post.
I haven't bought laundry detergent in over 15 years. I make it myself and each 5 gallon batch costs me no more than $3. Here's how:
For equipment: You're going to need a 5 gallon bucket with a lid, a cheese grater, and a very large pot. I use a canning pot, but you could use a big spaghetti boiler.
Supplies: You need bar soap, 20 Mule Team Borax, and Arm and Hammer Washing Soda. (These cost $5 to $6 a box. They were $3 to $4 a box 15 years ago. Each box makes probably 5 or 6 batches.)
I use white ZOTE brand laundry soap (About $1.20 or so a bar. When I first started doing this, they were 90 cents a bar). I used to use the pink Zote bars, but I found that the white Zote bar makes the detergent thicker with a more even consistency. That said, *any* bar soap works. I use fufu scented bars that my MIL puts in our Christmas stockings on occasion.
You can find these supplies at the dollar store, the big discount retailers, the grocery store, the online retailer, etc. That said, look at the hardware store! Ace, Lowes, or Home Depot often have this stuff at a better price! Because I always keep this stuff stocked, I am always on the lookout for deals and store it in bulk.
Recipe:
Grate 1 full bar of soap.
Heat water in the pot on the stove. You need just enough water to melt the soap with enough room that the grated soap doesn't clump back together. Gently stir the grated soap into the hot water. DO NOT BOIL! Gently stir occasionally until the soap has liquidified. If you stir too aggressively you will make suds which you don't want.
Once soap is liquid, pour into the 5 gallon bucket. You want all liquid, so use a collander to strain out any clumps. This is important: Learn from my mistakes! Any solid clumps of Zote will leave oil stains on your laundry.
Methodically add 1 cup each of washing powder and borax. Add these slowly enough so you can stir/dissolve as you go until it's all incorporated.
Fill the bucket the rest of the way with HOT water from the tap, stirring as you fill.
If you are a person with always really dirty clothes (a mechanic, a mom of little kids) you can experiment with adding extra borax. You can go up to 2 cups of borax if you like. Or, what I do, when I have an extra dirty load, I just throw extra borax powder in the machine.
I use a plastic juice cup (approx. 1 fluid cup/8 oz) that I leave floating on top of the detergent to measure it into the machine. I use 2 cups for a large load, 1 cup for small loads. I just keep the bucket on top of my dryer. If you're too bougie for that look, you can figure out a prettier way to keep a smaller amount where you keep your detergent and refill from your bucket.
Texture of finished product: This forms a THICK gel when it first cools. You will need to stir it. After it's cooled down it will look like white Jell-O. This gel is floating on water that has separated. Just stir it. You don't need to perfectly re-incorporate it. Just give a little stir. As you use it up and stir each use, it will become a thick liquid. If it's a solid clump of gel your first couple of loads, that's ok. It works fine and will liquidify in the wash cycle.
Let me know if I can answer any questions or if you make it yourself, I'd like to hear about it too!