I’m no STEM grad, but this doesn’t make sense to me. I’m not saying it’s wrong or that smarter people haven’t overcome my ignorance, I’m just confused. High pressure difference is needed to push water through the membranes. There is high pressure deep in the ocean. OK, but it’s the difference in pressures that make the filters work, right? So instead of creating high pressure with a pump, they’re creating lower pressure with a pump and letting the ambient high pressure push through? Seems like either way, they have to pump hard enough to create the same pressure differential. As I said at first, I know that I’m lacking in education here, it just doesn’t seem right to me.

Perhaps the pressure difference between a column of fresh water and the equivalent height of salty water is enough to tip the scales.