I laugh when I hear people talk about a water shortage. A shortage falsely implies there is a chance we could run out of water. While the total amount of water on the planet does not increase in volume, it also does not decrease. We have had the same amount of water we have always had, about 326 million cubic miles and will continue to have the same amount of water as long as the earth and the atmosphere is in tact.
What we do have are water distribution problems both at the micro and macro level. On the macro level about 97% of water is the oceans and another 2% is frozen in polar ice caps or glaciers. So 99% of the water on Earth is either too salty or too inaccessible for human use.
The water we borrow for our use comes from groundwater, lakes, rivers and wetlands. A little more than ½ of the remaining 1% of water is stored underground as groundwater. While a little less than ½ of 1% is stored in lakes, rivers, and wetlands and as vapor in the atmosphere.
From vapor to precipitation, water is in a constant state of motion. Like a very large terrarium, the Earth is a closed system. Plants transpire and oceans evaporate to form water vapor which cools in the upper atmosphere and falls back in the form of rain which recharges the lakes, streams and groundwater. Where the rain falls is not always convenient to where we would like it to be thus creating distribution problems at the micro level.
In the U.S. we need to borrow over 137 million gallons of water every day of which 60% goes to irrigation. Most of the 82 million gallons of water goes to massive irrigation to support large-scale farming in order to provide food. Irrigation makes it possible for the mega farms to grow crops in the dessert where nature never intended. Getting water to the desert is a micro distribution problem.
We are our own worst enemy when it comes to creating the micro distribution problem. Air, water and a little food are the only things we really need. Air is free, while water and food are commodities we can make available anywhere with the right amount of time and resources. The problem is the more we make an area livable by providing water the more the population increases and eventually the demand for water outpaces the distribution system especially in times of drought.
The nomads in the dessert learned centuries ago they must go to where the water is. When the economics of water distribution no longer makes sense, will the growth and development slow and will the populations adjust accordingly?
 As a side note I understand about metabolic water “creation”, but this process borrows water and is eventually returned to the water cycle…think human sweat or plant transpiration