Find the 3 eyes of the coconut at the stem of the coconut. Using a sharp knife or corkscrew pierce the eyes of the coconut.
Invert the coconut over a glass bowl or measuring cup and drain the coconut water. Reserve to drink.
Coconut water should be clear and sweet. If it is murky in color or has a rancid smell, it has gone bad, so discard it.
Using a hammer, break the coconut in half by hitting around the center to open it. Then, break each half again. You can also wrap the coconut in a towel first, then hit it with a hammer.
Using a butter knife, carefully remove the meat from the shell.
Cut the coconut meat into bite-sized pieces and add to a high-speed blender. Add warm water and process until smooth.
Pour the coconut milk mixture into a nut milk bag or muslin cloth in a bowl or large measuring cup.
Carefully close the top of the nut milk bag shut or bring the top of the muslin cloth together. Use your hands to squeeze out the coconut milk.
Pour milk in a container with a tight-fitting lid and store in the refrigerator for about 3- 4 days.