Combine water and coffee and place in a covered container (on counter or in fridge) for 12-24 hours.
Strain mixture using a cheesecloth, tea towel, or coffee filter (may take up to 1 hour with a coffee filter ).
To make an iced coffee, combine equal parts coffee concentrate and milk (or milk alternative), and pour over ice.
To make a frappe, in a blender combine 1 cup ice, 1/3 cup coffee concentrate, 1/3 cup milk (or milk alternative), and 1-3 Tbsp sugar (or sugar substitute). Blend until smooth.
To garnish, top with whip cream, shaved chocolate, cocoa powder or chocolate sauce.