Science

It's not nice and neat table salt. It usually comes to the form of an extremely toxic saline sludge. With who knows what other ingredients inside of it. It's a major problem with this kind of thing. If you use it on an industrial scale a scale large enough to provide water for a city for instance, then you're going to have enough output that will probably destroy whatever water source you're extracting water from. Better hope no one fishes in that ocean, cuz they all going to die.