A quick salt water desalination idea.
We have water towers for that high pressure. Why could we not use similar idea for high pressure desalination.
Pump seawater to an elevated level using solar power and then combine the water to a high pressure through the membrane. Perhaps its better to see if elevated freshwater can aid the pressure process instead.
So the idea is for a Large Water Desalination Tower. However the question is how to make it safe. You don’t want any risk of contamination.