The "drinkable book"

YouTube link.

From the outside, "The Drinkable Book" looks like a normal book. It's about an inch or two thick, with 20 pages. But these pages do a lot more than convey information. Each page also serves as a water filter, a valuable tool for preventing waterborne illness in the developing world...

The pages are about a millimeter thick and contain silver nanoparticles. The silver can rid the water of harmful microbes, but has very little effect on humans... To use the book, you rip one of the pages in half, slide it into the filter box (which doubles as a cover for the book) and pour contaminated water through. After a few minutes, the [bacterial count] is reduced by 99.9 percent and is comparable to U.S. tap water...

The books cost just a few dollars to make; each piece of filter paper costs about 10 cents. The filters can last a couple of weeks, even up to a month. So the entire books could provide the tools to filter clean water for about a year.