Shape the beef into 6 (1/2-inch thick) burgers. Cook the burgers in a 12-inch skillet over medium-high heat for 10 minutes or until well browned on both sides. Pour off any fat. Stir the soup, water and horseradish in the skillet and heat to a boil. Reduce the heat to low. Cover and cook for 5 minutes or until the burgers are cooked through. Top the burgers with the cheese and cook until the cheese is melted. Serve the burgers and sauce on the buns.