In a 5-quart Crock Pot, combine beans, bacon, leek, celery, thyme, and 10 cups water. Cover; cook on high setting until beans are tender, about 4 hours. Do not uncover while cooking.
Stir in bell pepper, season with 1 tsp salt and 1/4 tsp pepper. Cover; continue cooking until bell pepper is tender, about 20 minutes more.
To serve, discard bacon slices, if desired (but you would be crazy to); stir in 2 cups cooked white rice.