In a skillet, brown ground beef and onion; drain fat. Add the water, taco seasoning and all the tomato sauce; mix. Simmer for 20 minutes. Transfer to crockpot. Stir in macaroni and chopped green chilies. Cover and cook on LOW for 6 to 8 hours or on HIGH for 3 to 4 hours. In the last 30 minutes of cooking, top with shredded cheddar cheese.