Combine water and 1 teaspoon sugar in small bowl.
Sprinkle yeast over water; let stand 5 minutes or until surface bubbles to show yeast is working.
Combine flours, remaining sugar, pumpkin pie spice, baking soda and salt in large bowl; set aside.
In small bowl, combine buttermilk, pumpkin and melted butter.
Stir liquid ingredients and yeast mixture into dry ingredients until well blended.
Cover batter and refrigerate overnight.
To prepare waffles, heat waffle iron.
Pour in 1/2 to 1 cup batter, according to the size of the waffle iron.
Bake until waffles are done.