At the speed global water conversion from foul-to-fresh is spreading via inexpensive household solar 'desal' units, a few hundred billion people will not go thirsty.
The average human adult can survive for only two or three days without potable water, depending on the region, altitude, temperature, and humidity levels . Yet world population--7,164,000,000--has outstripped potable water supplies . At least a sixth of that population (1,100,000,000) does not have clean drinking water . Even with a 10% annual population decline projected at 8,300,000,000 by 2050, the situation will worsen (2).
Earth's remaining supply won't fill the void because 97.5% is salty and 1% is brackish groundwater. Of the 2.5% that remains, two-thirds currently are frozen, a third is potable , but 70% of that irrigates global food . The U.N.'s recent report declared that carbon intake is acidifying oceans . Some oceans have become oxygen-free "dead zones" . Some huge inland lakes (Erie) have grown so much toxic algae that last August tapwater of 500,000 Ohio residents were impacted . In short, the planet is rapidly nearing Samuel Coleridge's lifeboat poem of 1798: "water, water everywhere, nor any drop to drink" .
Other human activities also are significantly depleting huge reserves of remaining water either because of greed or environmental disregard. First for "high crimes" are multinational coal companies in Kentucky, Tennessee, Virginia, and West Virginia. Their "overburden" from mountaintop removal and effluent from coal washing has choked and poisoned valley riverine systems since the 1970s .
Next are multinational corporations fracking or mining for oil and gas under land leased from the ignorant, the equally greedy, or seized from holdouts by eminent domain. Each wellhead uses from 10,000,000 to 25,000,000 gallons of water . All are loaded with 500-750 chemicals--29 toxic to humans. Discharge is either deposited underground or in unlined open-air pits . Most of California's  pits and/or underground storage areas are near waterways [12, 13].
Shockingly, while 20 nations recently met in Lima, Peru for pre-Paris climate-agreement discussions, two multinational "Corporate Conquistador" companies--Repsol, Glencore-Xstata, Enel-Endesa--were busily draining vast water sources in that country for mining profits abroad and sending poisonous discharges into groundwater with impunity for locals to drink. Peru's government, like other weak nations, was "bought off" by those corporations .
Include Bolivia, India, Mexico--and U.S. state/municipal officials--overpowered by the bottled-water industry led by Bechtel, Coca-Cola, Nestle, Suez, Veolia, and Vivendi Universal all backed by the World Bank and International Monetary Fund . Include, too, the global garment industry swallowing two trillion gallons of freshwater annually, its "flow-through" of chemicals and dyes flushed into waterways . Now threatened are eight Midwest states dependent upon Nebraska's Ogallala aquifer for crops and drinking water if President Obama or Congress approve TransCanada Corporation's demand to run a tar-sands-oil pipeline nearby despite known risks of leaks and ground shifts breaking lines .
If the super-secret Trans-Pacific Trade Pact is signed by trade-desperate nations like the U.S., a multinational company will be able to ignore a nation's environmental laws by suing it, as is happening now in El Salvador, for denial of projected profits from resource extractions .
Water Shortages Setting off Global Crime Waves by the Desperate
None of these actions are considered criminal actions against humanity or Nature, but are when committed by people increasingly desperate for water: Spigot siphonings in Detroit ; armed gangs extorting water from India's villages ; shootouts between farmers and golf-course owners in the Philippines ; violence over water against corporations or governments in Argentina, Bolivia, Chile, Mexico and Peru [22, 23]; poisoning wells in Liberia ; black-market sales and hotlines in California .
Worrisome to governments is overthrow because of "social tsunami" over water shortages--and ailments like cholera and deaths from drinking polluted water--or privatization--will spark explosions not even armies will control [20, 3]. After all, bread shortages finally triggered the French Revolution, overwhelming an army, guillotining the 1%, and seizing their money and walled estates.
Small wonder that Defense Department's "Climate Change Adaptation Roadmap" report indicates it's preparing for trouble over vast population migrations seeking water and food . Even back in April 1961, President John F. Kennedy, mindful of upheavals over water, warned:
"If we could ever competitively, at a cheap rate, get fresh water from salt water it would be in the long-range interests of humanity, which would really dwarf any other scientific accomplishments. I am hopeful that we will intensify our efforts in that area" .
Today, governments that do not want to spend military budgets on firepower to quell revolutions over water would be well advised to say "no" to those gutting water supplies. Secondly, to invest in providing solar desalination systems to their citizens. Solar is far cheaper, simpler than fossil-fuel types that only Arab kingdoms can afford--and does little harm to the environment.
Conversion Processes Date From Antiquity
For thousands of years, billions have lived in areas requiring conversion of water or contaminated water to potable form, particularly in the arid Middle East. Sanskrit and Greek writings listed at least three methods of creating drinking water: exposing it to the sun (solar), filtering it through charcoal, sand, or clay (distillation), or by boiling . Aristotle conducted a distillation experiment in 350 BCE .