The best quencher for the thirsty is plain old water. Well, sort of. If the water is plain--that is, pure--then a quencher it may be. But if it is old, having sat around in an underground aquifer for millions of years, then maybe it isn’t so plain. In fact, it is quite likely to be contaminated with arsenic. Hundreds of millions of people throughout the world suffer from arsenic poisoning caused by impurities in their drinking water. If you drink surface water, you may not be safe, either. Arsenic is found in insecticides and herbicides and is a residue of landfill operations and gold-mining enterprises in some places.

Just in the nick of time, enter from stage right Nikolaos Nikolaidis, an associate professor at the University of Connecticut. Along with his graduate student, Jeff Lackovic, he has developed a simple, inexpensive but very effective filter for removing arsenic from drinking water. The filter has a 20-year life span and is no bigger than a regular filter you would put on a water line. It consists of iron filings and sand. When the iron corrodes, it removes the arsenic from the water. Nikolaidis and Lackovic have filed for a patent on the device. This is a case where simple chemistry has been utilized to engineer a wonderful result –- a device that truly improves the quality of life for millions upon millions.

Reference: http://www.oneworld.org/ips2/nov/bangladesh2.html