Preheat oven to 350 degrees F
Place the sliced apples in a 9x13 inch pan. Mix the white sugar, 1 Tablespoon flour and ground cinnamon together, and sprinkle over the apples. Pour water evenly over all.
Combine the oats, 1 cup flour, brown sugar, baking powder, baking soda and melted butter together. Crumble evenly over the apple mixture. Bake for 45 minutes.