Preheat oven to 325F. Grease a loaf pan. Combine flour, cocoa powder, baking soda, and baking powder in a bowl.
Mix the water, Dairy Dairy and vinegar in a large bowl. Let stand for 5 minutes to sour the milk. Beat in the sugar, vegetable oil, eggs, and vanilla extract. Stir the liquid ingredients into the flour mixture until just combined. Fold in the zucchini. Pour batter into the prepared pan.
Bake in the preheated oven until a toothpick inserted into the centre comes out clean, about 45 minutes. Cool in the pans for 10 minutes before removing to cool completely on a wire rack.