I've been making COLD BREW COFFEE in my "Toddy Maker" for over 40 years ~ and it's the only way my husband will drink coffee. This system (using the filters provided) will take out 90% of the acid (and that's what bothers most people) and about 90% of the caffeine ~ even using a pound of your favorite ground coffee (not decaf ~ I actually buy dark roast for him).
You get 2 filters, 2 black stoppers, plus the big white filter thingy ~ the glass container, handle and lid. I just wash out the filters, and they'll last for years! (The instructions may say that they last for 10 uses, and a pound of coffee will last 2 weeks ~ HAHA ~ a pound of coffee will only last my husband about 3 days!) You can buy more stoppers and/or filters separately (very inexpensive) on eBay, if necessary.
Forget what the instructions say ~ this is what I do:
Wet the thick white filter and stick it into the round indentation in the bottom of the white thingy. Put the rubber stopper underneath (and make sure it's in really well). Then put about 2 cups of water in the white thingy (TIP: If it "bubbles", then gently smash the filter down better into the indentation). Next put about 12 oz. ground coffee into the water and stir ~ start pouring more water in (and stirring) until it's about 4" from the top of the white thingy. Let it sit for about 5 minutes (the coffee will harden up a little) ~ then go back and stir with a spoon to loosen up the coffee, and pour more water in, stirring (until about 3" from top of white thingy). TIP: Put the whole thing into a bowl, in case it leaks!
Instructions say to let it sit 10-12 hours, and that's best. But sometimes I've waited too long to make it, so I've let it filter through after 6 or 8 hours instead (and it's fine). (I have a mini-espresso machine, and Hubby will have a cup from there in an emergency, but he's not used to the "oil/acid" or caffeine).
NOW, the TRICKY PART! Lift the white thingy up (I use the handle by stabilize with my other hand) and center it over the glass jar. Pull out the rubber stopper on the bottom and set the white thingy over the glass jar ~ and let the coffee concentrate drain into the glass jar. In theory, if you turn the lid of the glass jar over, that measurement is supposed to be the amount of concentrate to use in 8 oz. of water (but you can use more or less, to your liking).
You can heat up 8 oz. of water in the microwave for hot coffee ~ or use the concentrate (and remember that it IS a concentrate!) to make iced coffee.
If you're going camping ~ renting a condo ~ or anywhere else that you can heat water ~ just take your own concentrate in a mason jar!
EXTRA BONUS: Put those "used" coffee grounds on your acid-loving plants! gardenias, jasmine, camellias all love it! (I'll toss about 1/2 cup under them) If you have hydrangeas, the acid in the coffee grounds will turn the blossoms BLUE (if you do that before they start budding)