Lynn Haudenshield, age 12, of Pittsburg p Penna., or her question:

Can the world water supply run out?

Every day, billions of tons of water vapor go into the air from the damp and watery surfaces around the world. Every day, much of this vapor is turned into clouds and falls again as rain. This is Naturels water cycle that goes on endlessly without any help from us. It has been going on since the beginning of the world and there is no reason to expect it to change.

Much of this water is wasted. But every generation builds dams and reservoirs, wells and irrigation systems to save and make use of more usable of this wasted water. This means that our/water supply is getting more plentiful all the time.