Preheat the oven to 350°F. Lightly grease two 8 1/2" x 4 1/2" loaf pans.
In a large bowl, beat together the oil, sugar, eggs, pumpkin, and water.
Add the flour, baking powder, baking soda, salt, nutmeg, ginger, cinnamon, and vanilla, stirring well to combine. Mix in the nuts if you're using them.
Spoon the batter evenly into the prepared pans. Bake the bread for 60 to 80 minutes, or until a cake tester or toothpick inserted in the center of the loaf comes out clean.
Remove the bread from the oven and let cool completely on a rack before cutting. If time allows, wrap it well in plastic wrap after cooled and store it overnight before serving for the flavors to further develop.