I found this article at the Scienceblog interesting. It is about the alarming rate at which we, humans, are using up potable underground water.
One of the interesting statistics is that only 1 percent of ‘fresh’ water is free surface water. Groundwater (water contained in underground aquifers) accounts for—or did once—30 percent of the available fresh water on the planet. Basically all of the rest is tied up in the polar ice caps and what is left in the various glaciers around the place.
To visit the Scienceblog, which, in my opinion anyway, is well worth the occasional visit, then go here.
To see the article I am referring to go here.