Cut ribs into serving-size pieces. Place in a 5-quart slow cooker and pour barbecue sauce over ribs. Sprinkle with garlic. Cover and cook on low for 6-7 hours or until meat is tender.
Remove ribs and keep warm.
Strain cooking liquid into a small saucepan; skim the fat. Combine arrowroot and water until smooth; stir into cooking liquid. Bring to a boil; cook and stir for about 2 minutes or until thickened. Spoon sauce over the ribs.