To be absolutely candid, I really have no idea what would happen. It has not been tried.
One of the problems with bulk export in most situations is that it's simply not economical. You're not going to make money; it will cost more to do than it will be worth. So it's not likely to happen any time in the near future.
Certainly, there is the export of bottled water, which is essentially something of a luxury item in a North American context. I don't think there would be anything to prevent anybody from bottling water and shipping it.