In a large container, stir together coffee and water.
Cover and brew for 12-24 hours, to taste.
Filter the coffee concentrate through a strainer lined with a coffee filter into a clean container, and refrigerate.
Covered and stored in the refrigerator, this cold brewed coffee should last 3-4 weeks.
To make a perfect glass of homemade iced coffee:
Fill a tall glass with ice (or to keep your iced coffee stronger, use coffee ice cubes!) and pour in cold brewed coffee to about ¾ full.
Stir in your favorite sweetener. I like to use this double strength simple syrup for cold beverages. Drizzling in sweetened condensed milk is another decadent option.