Measure water into large bowl. Sprinkle yeast over water; let stand 5 minutes.
Stir in 2 cups flour until smooth. Stir in remaining flour and salt, stirring until dough pulls away from sides of bowl. Cover with plastic wrap and refrigerate overnight
Remove dough from refrigerator 2 hours before shaping and let rise, covered in a warm place until almost double in size.
Coat a dark, rimless baking sheet with cooking spray. Coat work surface with cooking spray and dust with flour. Transfer risen dough onto work surface; divide into 3 pieces. Shape into long, narrow loaves (about the length of the baking sheet). Place loaves on prepared baking sheet, cover and let rise until puffy, about 45 minutes.
Preheat oven to 450. Make 4 to 5 diagonal slashes on each loaf with a sharp, serrated knife. Spritz loaves heavily with water. Bake until loaves are golden 25 to 35 minutes. Cool on wire rack.