Add the water, beans, sausage, red bell pepper, celery, Creole seasoning, thyme, cayenne pepper, and bay leaf to the bowl of a slow-cooker. Add the lid and turn the heat to "HIGH'. Let it cook for 6 hours, stirring once or twice. After 6 hours, use a spoon to fish out a bean to test. If it is tender, turn off the heat. If it is still underdone, replace the lid and cook for another hour or until the beans are tender. Remove and discard the bay leaf.