One thing I thought I would ...

One thing I thought I would mention, one concern with vacuum is the membrane sealing itself. It may be possible that once the membrane is saturated with water, that water's ability to adhere would keep channels open for the water molecules to move through. When water is "compressed" (water is not considered compressible) or pressurized that it might become excited and expand. And when something is under or in a vacuum, normally that element or molecule expands or becomes more excited. While it may be counter-intuitive, water may conserve itself due to an absence of pressure effecting it. If so, then water molecules might be in the lowest state (it's densest form). If so, this may also increase the cohesion of water molecules which could help to increase the efficiency of the process.