Once you taste really good cold brew, it's very hard settling for ordinary iced coffee. Coffee shops and gourmet grocers are aware of cold brew's charms, and they now charge a premium for it. My local Starbucks charges $3.98 for cold brew (for comparison's sake, that roughly converts to £3.10, AU$5.75), an extra 64 cents on top of their already pricey $3.34 large iced coffee. Adding "house-made vanilla sweet cream" brings the cost up to $4.51.
Now consider that a 3-pound bag of Kirkland Colombian Supremo coffee ($16 at my neighborhood Costco; converted £12.50 or AU$23) can make five 24-ounce batches of concentrated cold brew. With each batch enough for 12 separate drinks, that's 60 drinks for $16 ( £12.50, AU$23) compared with three to four bought at the cafe. That's why you should definitely brew your own cold brew at home. You'll not only avoid the high retail markup, but you'll always have delicious chilled coffee on hand, too.
Why do the cold brew?
Unlike regular iced coffee made from hot-brewed drip that's then cooled and poured over ice, cold brew is made with room-temperature (or colder) water from the start. You pour that water over a greater-than-normal quantity of coffee grounds, let it steep for 12 hours or more, and the result is a coffee drink that's sweet, rich and velvety-smooth, with no bitterness or acidity.
Cold brew should also be quite strong. Ideally, each batch uses double the coffee grounds called for to make a stiff pot of French press. But despite its potency, cold brew is remarkably easy to drink, especially when you cut it with ice, water, milk or even a little simple syrup.
Frankly, it's the perfect coffee companion during steamy summer months. The flavor of cold brew concentrate won't degrade after sitting in melting ice either, a failing of conventional iced coffee.
There are many different ways to make cold-brewed coffee, but at its core, the procedure is the same. You first start with coffee beans ground as coarse as your burr grinder will process them. Shoot for the texture of sand or breadcrumbs, not a fine powder.
Next, you'll want to make sure your coffee-to-water ratio is high enough to yield a strong liquid concentrate. I tend to shoot for one part coffee to four parts water (1:4), double the amount of coffee grounds called for by a typical pot of French press (1:8) and four times what's necessary for a drip machine (1:16). If you begin with 40 ounces (1.2 liters) of water, then expect to combine this with 10 ounces (284 grams) of ground coffee.
Choose your container
You can steep coffee for cold brew in just about any watertight vessel, from mason jars or glass pitchers, to even plastic buckets. What's most important is to select a brewing chamber large enough to contain both your volume of water and the sizeable quantity of coffee grounds. The container also must be compact enough to store while its contents are brewing.
If you plan to brew in your kitchen fridge, then a small mason jar, French press or pitcher will work best. If you're making massive quantities of cold brew, you should consider brewing at room temperature unless you have adequate refrigerator space.
It's a waiting game
The big trade-off you make for brewing coffee at low temperatures is increased brewing time. A batch of cold brew requires between 12 and 24 hours to steep properly, no matter if it's sitting in the fridge or on your kitchen counter.
One approach is to prepare your cold brew during daytime hours or right before bedtime, then let it steep overnight. Another tactic is to make a large amount that's enough to last for a week or two. Hopefully this will give you time to brew more coffee before you run out completely.
Strain the grounds
Perhaps the most difficult step in the cold-brew process is separating the coffee grounds from your liquid. A few popular ways include brewing using a French press and using its plunger to filter out coffee solids. A standard paper coffee filter works, too, along with metal mesh sieves, cheesecloth or even a combination of all three.
In my experience, these DIY methods don't work as well as a dedicated cold brew appliance. I've found that paper and metal filters tend to strain slowly and create more mess than devices like the $49 Oxo Cold Brew Coffee Maker (£37, AU$64) and the $25 (£19, AU$32).
Pour, enjoy, repeat
Because you use a lot more beans making this kind of coffee drink compared with ordinary drip, cold brew is incredibly potent. Don't be afraid to dilute the liquid with chilled water, lots of ice, or milk to stretch out your supply.
I also recommend making some simple syrup to use as a handy sweetener. Even a touch of it will enhance the fruit-forward flavors of medium- and light-roasted coffee grounds, or the earthier, chocolate notes typical of a dark roast. Syrup will also dissolve into cold drinks much faster than solid sugar crystals.
Now that you have the overall picture of how to cold-brew coffee at home, you'll be making batches yourself in no time. I'll bet you'll have fun -- and even save a little money in the long run, too.
Update, May 24, 2019: This article was originally published in May, 2016 and is updated periodically.