> Geological mana, like biological mana, has an owner, and therefore cannot be used by any human. Waste mana has no owner (null owner).
At the beginning of the story, waste mana is undetectable and unusable, although theory predicts both that it exists and that it obeys the same laws as biological and geological mana. As far as anybody knows, waste mana sinks back down into the Earth where it is presumably unrecoverable. It is theoretically possible to capture escaping waste mana using a specialised mana battery known as a "bilge".