system
Given the following post, respond as if you're commenting on Reddit:
human
How could the world eventually run out of water?


There's always talk about the world running out of water.  It's an intriguing situation to me, but do we ever really think what would happen if it did?  I know that Earth may not be *running* out of water, but rather, the distribution of it has become rather complicated.  But please, humor me:

What are some scientific/natural reasons why the planet could run out of water, or how the chemistry of the world's water can be changed to something undrinkable?

I'd like to know if there are any scientific bases for such a scenario, and the timeline on which one could occur.
gpt
As others have pointed out, the issue is potable water, and we are not "running out" but overtaxing the supply.

Water, even when consumed or used for irrigation, does not magically disappear. Some of it gets stored in the tissues of living organisms, some trickles down into the water table, some evaporates and becomes atmospheric water vapor, some runs off into streams and from there eventually to the ocean.

The "water cycle" we learned about in grade school is essentially a "factory" with a finite capacity. As demand grows, it outpaces the capacity of the factory. The factory still produces the same amount of potable water, but there is not enough to meet growing demand.