Lightly spoon flour into dry measuring cups; level with a knife. Combine flour and salt in a medium bowl. Place milk, 1 cup water, butter, and eggs in a blender; process until combined. Add flour mixture to blender; process until smooth. Cover and refrigerate 1 hour.
Heat a 10-inch crepe pan or nonstick skillet over medium-high heat. Coat pan lightly with cooking spray. Remove pan from heat. Pour a scant 1/4 cup batter into pan; quickly tilt pan in all directions so batter covers pan with a thin film. Cook about 1 minute.
Carefully lift edge of crepe with a spatula to test for doneness. The crepe is ready to turn when it can be shaken loose from the pan and the underside is lightly browned. Turn crepe over; cook 30 seconds on other side.
Place crepe on a towel; cool completely. Repeat procedure with cooking spray and remaining batter, stirring batter between crepes. Stack crepes between single layers of wax paper or paper towels to prevent sticking.