Preheat oven to 350degrees. Combine first eight ingredients. Whisk together eggs, pumpkin, oil and water; stir into dry ingredients just until moistened. Fold in walnuts and, if desired, raisins., Pour into a greased 9x5-in. loaf pan. Bake until a toothpick inserted in center comes out clean, 65-70 minutes. Cool in pan 10 minutes before removing to a wire rack.