Whisk in 1 1/2 cups water and continue mixing for a few minutes, until batter is "smooth and elastic" (stated in the original recipe).
Cover your bowl with plastic wrap and let rest in the refrigerator overnight.
When ready to make the crepes, mix the milk and the 2/3 cups water into the batter.
Heat a 10 inch pan over medium heat. Spray the pan with nonstick cooking spray or brush with some melted butter.
Pour in 1/4 cup of the batter and quickly swirl it around the pan till evenly coated. Cook for 2 minutes, or until the edges start to peel away from the side of the pan and the crepe starts to brown. Flip the crepe over and cook the other side for about one or two minutes. Repeat with the rest of the batter.