In a Dutch oven, cook sausage, mushrooms, green pepper and onion over medium heat 5-6 minutes or until sausage is no longer pink and vegetables are tender, breaking up sausage into crumbles; drain., Stir in pasta, pizza sauce, water, Italian seasoning and salt; bring to a boil. Reduce heat; simmer, covered, 10-15 minutes or until pasta is tender. Remove from heat; sprinkle with cheese. Let stand, covered, 5 minutes or until cheese is melted.