Not long ago the US Military working in conjunction with TARDEC (Tank-Automotive Research, Development and Engineering Center) designed a system that allows Army vehicles to create perfectly drinkable water
via the condensation of the engine exhaust system.
The system creates on average 3.5 gallons per day.
Imagine implementing this system world wide.
There are over 600 million vehicles
in use word wide currently.
At 3 gallons per day that would be 1.8 Billion gallons of water created every day