Place the coffee grounds in a one-quart pitcher or similar vessel. Make sure that you can cover it, even if it's with some plastic wrap. Make sure that all the water and the coffee grounds can fit, and you can store it in the fridge.
1 cup whole coffee beans freshly and coarsely ground
Pour the water over the coffee grounds.
Stir to combine for a minute or until all the coffee grounds are thoroughly wettened.
Cover and let it steep at room temperature for 12 to 24 hours. 18 hours is my sweet spot.
When ready to strain the coffee, place a nut milk bag over a large deep bowl (see other filter options in note).
Pour the coffee concentrate into the milk bag.
Close the bag, and use your hands to let the coffee steep and drip out entirely into the bowl.
Discard the coffee grinds or use them as a body exfoliator or fertilizer for acid-loving plants.
Transfer the cold brew into a pitcher with a lid—you can also use the same vessel in which the coffee grounds have steeped, but rinse it out first.
Refrigerate and store for up to one week.
To serve: Fill a tall glass with ice and pour over the cold brew. If desired, leave enough room for milk or cream or dilute with water if too strong. Enjoy as-is, or add your favorite flavors or sweeteners.