Set the oven rack to the middle position and preheat to 350°F (175°C). Grease two 9x5-inch loaf pans and line the bottoms with parchment paper, leaving overhang on the long sides.
In a medium bowl, whisk together the flour, baking soda, baking powder, salt, cinnamon, nutmeg, cloves, and ginger until evenly distributed with no visible streaks.
In a large bowl, whisk the granulated sugar and brown sugar into the vegetable oil. Add the eggs one at a time, whisking well after each, then whisk in the pumpkin puree, water, and vanilla until smooth.
Add the dry mixture to the wet ingredients in two additions, folding gently with a rubber spatula after each. Stop as soon as no dry streaks of flour remain; a few small lumps are fine.
If using walnuts, pecans, or chocolate chips, toss them in a tablespoon of flour first, then fold into the batter with just two or three strokes of the spatula.
Divide the batter evenly between the two prepared pans and smooth the tops. Bake for 60 to 65 minutes, rotating the pans halfway through, until a toothpick inserted into the center comes out clean.
Let the loaves cool in the pans on a wire rack for 15 minutes, then use the parchment overhang to lift each loaf out and transfer directly to the rack. Cool completely, about 1 hour, before slicing.