Humans need not just water, but fresh water. That is why this problem exists despite the planet's surface being 70% water. In addition, many people live in areas with no water supply, fresh or otherwise, and their needs must be met out as well. This donation would be crucial to developing a world with less people being in unnecessary need. Hopefully, after this plan's implementation more people will be able to use more water.
This includes for things other than drinking, such as irrigation, hygiene, and all the other uses taken for granted by much of the first world. This plan would extend these privileges around the world, making it a worthy cause to support. Making parts of the world capable of independence from constant external support, since they would be producing their own water for their own purposes.In addition, this plan would create jobs in these places which are invariably poor, as the construction occurs, and to run the factories afterward. This stimulus to otherwise dying places compounded with the new necessity of water being supplied consistently could turn many otherwise desolate places into growing, or at least not diminishing economies.
In conclusion, the donation of $20 billion could become a life saving change in the world, helping much of the world develop. The worldwide cleansing of water could help millions of people around the world, who need something as simple as water to drink.

