Heat oven to 350°F. Arrange taco shells on ungreased cookie sheet. Bake 5 to 7 minutes or until hot. Meanwhile, in 10-inch skillet, cook ground beef over medium-high heat 5 to 7 minutes, stirring frequently, until thoroughly cooked; drain. Stir in taco seasoning mix and water. Reduce heat to medium; cook about 5 minutes, stirring frequently until water has evaporated.