Cook ground beef, onion and green pepper in large skillet over medium heat 5 minutes or until beef is no longer pink; pour off drippings. Add tomatoes, water and taco seasoning; simmer 5 minutes, stirring occasionally.
Toss pasta with meat mixture. Spoon 3 cups of mixture into an 11x7-inch baking dish. Sprinkle with 1 cup cheese; top with remaining meat mixture. Cover with foil; bake in preheated 375°F oven 30 minutes. Uncover; sprinkle with remaining cheese. Return to oven 5 minutes or until cheese is melted.