Add coffee grounds to the water in a large pitcher. Refrigerate overnight (or 24 hours).
Place a fine sieve in a large bowl (or another pitcher) with a double layer of cheesecloth, paper towels or coffee filters inside the sieve. If you don't happen to have a sieve, use the finest strainer you have, and line the strainer with the same things. Pour the cold brewed coffee through the lined sieve/strainer. The coffee grounds should be left behind with the cheesecloth/paper towels/coffee filters catching them. If you still see grounds after straining, go ahead and strain a second time. Store the strained cold-brew coffee in a large pitcher in the refrigerator for up to 2 weeks.
Serve cold brew coffee over a tall glass of ice. If you're really motivated, you can make some ice cubes from the cold brew coffee and use those so your iced coffee doesn't get watered down at all.
Add ins: Cold brew coffee is delicious with a tablespoon or two of sweetened condensed milk and a splash of regular milk too.
Notes
Adding sweetened condensed milk and/or milk to your cold brew coffee will change the nutritional information.