Pour ground coffee in a large container. Add water and stir to combine. Cover and let sit for 24 of the longest hours of your life!
Place several layers of cheesecloth in a strainer and pour coffee extract into a jar or pitcher (I use glass because I can see the gorgeous extract through the glass (so pretty!) and glass doesn't mess with the flavor).
Cover and store extract in the refrigerator for up to 2 weeks.
When ready to serve, pour a scant one-third cup of concentrate in a glass and top it off with two-third cup of filtered water, a few ice cubes, and a straw.