Cook the chicken in a 10-inch nonstick skillet over medium-high heat until well browned and cooked through, stirring often. Stir in the soup and water and cook until the mixture is hot and bubbling.
Place the tortillas onto 2 baking sheets. Spoon about 1/3 cup chicken mixture onto half of each tortilla. Brush the edges of the tortillas with water. Fold the tortillas over the filling and press the edges to seal.
Bake for 5 minutes or until the filling is hot. Cut the quesadillas into wedges and serve with the salsa.