Water is due to be more expensive than oil 2020, is we continue with high pressure desalination. We just need to use our brains and high school physics.
Nature makes fresh water, by evaporating sea water over a huge area. But if we took the air down to -1 atmospheres, the water would boil. Leaving the salts behind. Not very practical – we all need to breath.
So we do it in a 1m tube. Metal or glass. Before the sea water reaches the top of the tube, it boils. Losing all salts. So where ever we can create 1m of vacuum head, we have an infinite source of water- either from the seas, or rivers of the world.
In the hot countries, we use a solar vacuum pump. To supply the head.
E=PV So here E=V.
So a 2kW pump, will yield 2,000 litres a second. Realistically, 200 L, pumped into a tank or holding reservoir.
And pumping water vapour takes 1/1000th of the power compared to pumping water.
We have no filter pads that need changing. We have no dangerous pressures. A leak here produces a hiss, you don't lose a limb.
So we irrigate the dry lands, and import top soil from a river delta. We plant grass seed – instant Savannah – gobbling up CO2 from the air. It will actually increase plant and animal life on Earth – so we also get more CO2, for plants to take in.
In the Arctics, we have high winds. So we drive a little wind turbine. And get as much liquid water as we wish.
In countries short of water, we keep reusing the water as is goes down stream – each time ending up as saltless desalinated water.
So we have just changed the world into a much better place. The water will cost less than reservoir water in the temperate lands.
In countries like the UK, we have just broken the monopoly of the water companies. We can have loads of little water firms, sucking pure water out of the rivers.
And selling it for 1/10th the over priced mains water coasts today.