Pour ground coffee into a French press, pitcher, or mason jar, and pour water over the grounds.

Stir well and cover the pitcher with plastic wrap. Let it steep at room temperature for at least 12 hours, up to 24 hours, depending on how strong you want the cold brew.

Pour the mixture through a fine-mesh strainer into another pitcher or container, and keep in the fridge until you're ready to use.

To serve, add cold brew concentrate and cold water into a glass with ice. The ratio of concentrate to water depends on how strong you like your coffee.