Mix flour and eggs with whisk. Slowly add milk and water, stirring to combine. Add salt and butter; beat until smooth.
Heat lightly oiled pan over medium-high heat. Pour batter using ¼ for each crepe. Tilt so the batter coats evenly.
Cook for about 2 minutes, until the bottom is light brown. Loosen with spatula, turn and cook other side. Serve warm.