Add the bones, celery, carrots, onion, garlic, herbs, salt, and pepper to the slow cooker.
Add the apple cider vinegar and water to the slow cooker. If you still have space in your slow cooker, you can add additional water so it reaches the top of the slow cooker.
Slow cook on low for at least 12 hours.
Allow broth to cool slightly, and using a ladle, scoop the broth through a fine mesh strainer into a large pot, bowl, or multiple containers.
Transfer to airtight containers and allow them to cool before refrigerating or freezing.