Put chicken into the crock of a slow cooker. Sprinkle taco seasoning over the chicken. Layer diced tomatoes with habaneros, onion, celery, and carrot over the chicken, respectively; top with salsa. Pour water over the entire mixture.
Cook on Low until the chicken is easily shreddable, 6 to 8 hours. An instant-read thermometer should read 165 degrees F (74 degrees C).
Shred the chicken with 2 forks and stir with the salsa mixture.
