Cook the sausage in a 10-inch skillet over medium-high heat until it's well browned, stirring often to break up the meat. Pour off any fat.
Stir the soup, water, tomatoes and tortellini in the skillet and heat to a boil. Reduce the heat to low and cook for 5 minutes or until the tortellini is tender.
Stir in the basil and serve with the cheese, if desired.