In reply to David Hooper:
I'd replace it, black mold is a serious threat if ingested, it’s the bacteria that are inside the system that’s dangerous to you.
If you want to try to clean it, then do it thoroughly, with bleach, Chemical reactions in the bleach will kill everything but you’ll need to get that solution into all areas of the water system, let it soak a while in very hot water to clean the entire system from bladder to the end you bite to drink.
Bicarbonate soda is ideal for the mold removal as it’s abrasive; you can get cleaning utensils for the camelback to clean tubes etc. The problem is the bits you can’t reach, so really it would be ideal to replace the whole system otherwise.
Jason