Preheat oven to 175C. Spray one 9x5x3 inch loaf pan with a non-stick cooking spray. In a medium bowl, beat the white sugar and margarine or butter until smooth and creamy. Beat in the eggs, water and bananas with the sugar mixture until it is well blended. Mix in the flour, baking soda, salt and baking powder just until the mixture is moistened. Bake at 175C for about 60 minutes. Bread is done when the top is firm to the touch and a golden brown colour. Time will vary according to loaf size and oven type. When bread is removed from oven, allow it to cool for 10 minutes, then remove from pan and let cool on a rack.