Measure the flour, sugar and salt into a small bowl and stir to mix.
Measure the milk, water, melted butter and eggs in a blender or mixing bowl and beat together briefly.
Dump the dry ingredients on top of the wet and blend or whisk until smooth.
Store the batter in the fridge for at least an hour before using. The batter will keep for a day or so.
To cook the crepes, coat a crepe pan with cooking spray and bring to medium high heat.
Use a 1/4 cup measure to pour the crepe batter into the hot pan, immediately lift the pan from the heat and turn to spread the batter all the way around the sides of the pan. (Adjust the amount of batter needed to fit the size pan you're using)
Cook the first side for about a minute. It should release and slide around the pan when ready to turn.
Flip and cook the other side. The finished crepe should be dry and brown in spots, but not brown all over like a pancake. Adjust the heat as necessary to prevent over-browning.
Avoid stacking the flat crepes on top of each other. You can either fold them or place a piece of waxed paper in between them.
Crepes will hold in the fridge for a couple days or a month in the freezer.