Preheat oven to 350 degrees. Grease and flour three 7x3-inch loaf pans.
Stir flour, sugar, baking soda, salt, nutmeg, and cinnamon together in a large mixing bowl until well blended. Add mashed pumpkin, oil, water, and eggs; beat with an electric mixer until well combined. Fold in walnuts. Divide batter evenly among the prepared pans.
Bake in the preheated oven until a toothpick inserted in the center of each loaf comes out clean, about 1 hour.
Remove from the oven and set pans on a wire rack. Let cool completely before slicing.
Makes three 7x3" loaves.
You can use pumpkin puree instead of cooked fresh pumpkin, and raisins instead of walnuts if desired.