Combine water and broth; bring to a simmer in a large saucepan (do not boil). Keep warm over low heat.
Cook bacon in a Dutch oven over medium heat until crisp. Remove bacon from pan, reserving 2 teaspoons drippings in pan. Crumble bacon; set aside.
Return pan to medium heat. Add red onion; sauté for 3 minutes. Add barley; cook 2 minutes, stirring constantly. Add wine and salt; cook 2 minutes or until liquid is nearly absorbed, stirring constantly. Add broth mixture, 1/2 cup at a time, stirring until each portion of broth mixture is absorbed before adding the next (about 45 minutes total). Stir in bacon; cook for 2 minutes. Remove from heat; stir in radicchio, cheese, and pepper. Serve immediately.