Heat a large skillet over medium-high heat, and stir in the ground beef and onion. Cook and stir until the beef is crumbly, evenly browned, and no longer pink. Drain and discard any excess grease.
Layer the coleslaw mix, rice, and ground beef in a 9x13 inch baking dish. Combine the soup and water in a medium bowl. Pour the soup over the top of the ground beef. Cover with foil.
Bake for 1 hour and 15 minutes, or until the rice is tender.
