Mix ground coffee and water in a big container. Cover and let sit at room temperature for eight hours or overnight.
Using a fine mesh strainer lined with cheesecloth, strain the coffee/water mix, reserving liquid and discarding the grounds. Transfer coffee to the fridge so it can cool.
fill a cup with coffee-flavored ice cubes (simply freeze coffee overnight in an ice tray) and fill it 2/3 with the coffee.
Stir in about two tablespoons of sweetened condensed milk.