Preheat oven to 350°F. Grease and flour two large (9 by 5-inch) loaf pans, or coat with nonstick cooking spray.
In a large bowl, whisk together flour, baking soda, salt, cinnamon, and nutmeg. In another large bowl, blend together pumpkin puree, sugar, oil, water, eggs, and vanilla until well incorporated. Slowly add in flour mixture, mixing until just blended. Fold in chocolate chips.
Divide batter between prepared pans. Bake for one hour, or until a toothpick inserted in the center comes out clean. Cool in pan for 5 minutes before turning out onto a wire rack to cool completely.
Loaf pans and muffin pans come in a variety of sizes, so the size of your pans will dictate how many loaves/muffins you get. Fill each pan about 2/3 full of batter. Below are the sizes of pans I've used and approximately how long they've needed to bake. If your pan sizes fall between these options, adjust the time accordingly. Regardless of the pans you use, consider these times a guideline, and bake until a toothpick inserted in the center comes out clean:
Two 9 by 5-inch loaf pans -- 60 minutes
Three 7 by 3-inch loaf pans -- 50 minutes
Six mini loaf pans -- 40 minutes
Approximately 3 dozen regular muffins -- 20 to 22 minutes
Approximately 100 mini muffins -- 12 to 14 minutes