Cook noodles according to package directions until almost tender; drain. In a large skillet, cook beef, onions and the green pepper over medium heat for 10- 12 minutes or until beef is no longer pink; drain off fat. Stir in noodles, soup, cheese, water and chili sauce. Transfer to a greased 8 inch square baking dish.
Toss bread crumbs with melted butter; sprinkle over casserole. Bake uncovered, at 350°F for 35 to 40 minutes or until bubbly and golden.