Preheat oven to 350°F and place rack in centre of oven. Line 20 regular-sized muffin cups with paper liners. In a large bowl whisk together sugar, flour, cocoa powder, baking powder, baking soda and salt. In another large bowl, whisk together eggs, mashed bananas, water, milk, oil and vanilla extract. Add the wet ingredients to the dry ingredients and stir until combined. Pour or scoop batter into muffin cups, filling almost full, and bake 20-25 minutes, or until a toothpick inserted in centre of cupcake comes out clean. Remove from oven and let cool on a wire rack. To make chocolate cream cheese icing, melt chocolate chips and water in microwave or on stovetop, stirring until smooth. Let cool to room temperature. In medium bowl, beat cream cheese, chocolate mixture and icing sugar until smooth and creamy. Spread over cupcakes.