To prepare sauce, combine water, tomato paste, oregano, pizza seasoning, salt, garlic powder, and black pepper in a medium saucepan. Mix well and bring to a boil. Reduce heat and simmer ten minutes. Preheat oven to 375. Prepare a 8" square dish with cooking spray; set aside. Cook pasta according to package directions. In a mixing bowl, combine pizza sauce, pasta, pepperoni, bell peppers, parmesan cheese, and oregano. Mix well. Spread mixture evenly into prepared dish. Sprinkle top with cheese. Cover with foil and bake for 30 minutes, or until heated through and cheese has melted.