In 4 1/2- to 6-quart slow-cooker bowl, combine water, carrots, celery, onion, bay leaves, thyme, 4 teaspoons salt, and 1/2 teaspoon pepper. Place whole chicken on top of vegetables. Cover slow cooker with lid and cook as manufacturer directs on low setting 8 to 10 hours or on high setting 4 to 5 hours.
Transfer chicken to cutting board. Discard bay leaves. Add noodles to slow-cooker bowl; cover with lid and cook (on low or high) 20 minutes.
While noodles cook, remove and discard skin, fat, and bones from chicken; shred meat.
Skim fat from soup and discard. Return chicken to soup to serve.