Combine all the seasonings in a small bowl and rub evenly over roast. Place meat in a 6-quart slow cooker. Add water. Cover and cook on LOW for 6-8 hours or HIGH for 4-5 hours or until pork is very tender.
Remove pork to a large cutting board or platter and let rest for 10-15 minutes. Pull, slice or chop to serve. Serve in buns with barbecue sauce.