The new desalination plant in Texas uses the old idea of forcing high pressure water through filters. This is expensive and dear – using pressures of +8 atmospheres.
They should turn the pumps around. We want just 1 atmosphere of vacuum - -1 atmospheres. At this pressure all water boils. Both brown river water and sea water.
It now loses its salts and contaminants – it loses all impurities. We suck out pure water. Like it has boiled – as it has. By definition water turns into vapour at -1 atmospheres. Even ice.
No high power required. No heat. Cheaper than reservoir water. We transfer the water vapour to a high reservoir – using a chain of solar powered pumps.
As we vent the pressure, the vapour turns back into liquid water – giving up heat to the air. So we fill the reservoir with liquid water, we can use for drinking or growing crops. It is as pure as condensed steam – as it is.
For 2% the cost of high pressure desalinated water. Areas will access to the sea or a river, can make their own fresh water – and sell it to other water consumers in the area.
Undercutting present water companies.