In a large jar or pitcher, mix the coarsely ground coffee with cold water.

Using a spoon, stir the mixture gently to ensure all the coffee grounds are saturated.

Cover the jar or pitcher with a lid or plastic wrap and let it steep at room temperature for 12 to 24 hours (minimum 12 hours for best flavor).

After steeping, strain the coffee through a fine mesh strainer or coffee filter into another container to remove the grounds.

Transfer the strained concentrate into a clean jar or bottle and store it in the refrigerator for up to two weeks.

To serve, fill a glass with ice and pour in equal parts coffee concentrate and cold water or milk, then stir gently.

Optionally, sweeten with sugar, simple syrup, or flavored syrups to taste.

Experiment with additions like vanilla extract or cinnamon for extra flavor.