Making fresh water.
Nature does not use dangerous and expensive high pressures! Where it does, the water bubbles pout of the Earth as warm water and steam. Most fresh water is evaporated from the seas. To fall as rain.
So water boils ever at 1 atmosphere at 0oC. But it takes a large area. But on Everest you can't make tea, as water boils at only 70oC – too cold to drew tea. Even ice sublimes into water vapour with 1 m of vacuum head.
This is not a lot of pumping! So we require no expensive filter – that needs to be changed often.
We HAVE A 4 GALLON TANK, AND A HBAND PUMP. As we pump, we start to get out water vapour, which hits a metal pout, and comes out as pure, desalinated water – to fill our jug.
We continue to pump out water, until we have ½ a gallon left. We open up the device, and poor the dirty liquid down a drain.
We fill up with dirty river water, and pump out our pure, drinkable water.
Oxfam will give a village 20 such pumps, which acids the need fro mains water. We can draw water from a bore hole, which is polluted with bacteria and fetal matter – it does not matter.
We such out enough pure water for our needs, and hand the device on to the next family.
If we want to get nautical, we use a solar powered vacuum pump, and fill a pure drinking water pond.
Massively cheap – using no expensive water filer or mains power. It will even turn sea water into pure drinkable water, for the price of the device. Which will last for 50 years.
Free water for the world. So important for countries like India.