Wilderness Survival: filtering water with charcoal?

Teach them how to carry a pack with essential gear at all times. That will promote their survival a lot more than drinking charcoal-filtered lye. I am not a fan of survival shows because they neglect to demonstrate preparedness for outdoor recreationists. Lack of planning causes most mountain rescues and body recoveries. Pack the right gear and avoid desperate survival techniques. If they know how to filter through charcoal and fail to pack adequate firestarter equipment, they are screwed.