Scientists have devised a "Drinkable Book" with chemically altered pages that could make contaminated water pure by 99.9%.
A team from Carnegie Mellon University in the US, tested the book in Africa and reported how each page -- containing bacteria-killing metal nanoparticles -- made water polluted with raw sewage, as safe as North American tap water.
Designer Dr Theresa Dankovitch came up with the idea while studying the properties of paper.
Although silver's bacteria-killing properties have been known, Dankovitch says that no one had thought to put it in paper before.
Each page can clean up to 100 litres of water and one book can purify a person's water supply for a whole year.
All that is required is a holding device into which the pages have to be slotted.
Dankovitch is presenting the findings from trials she conducted in Bangladesh and Africa at this year's American Chemical Society meeting.
"In Africa, we wanted to see if the filters would work on 'real water,' not water purposely contaminated in the lab," she said.
"One day, while we were filtering lightly contaminated water from an irrigation canal, nearby workers directed us to a ditch next to an elementary school, where raw sewage had been dumped.
"We found millions of bacteria; it was a challenging sample.
"But even with highly contaminated water sources like that one, we can achieve 99.9 percent purity with our silver- and copper-nanoparticle paper, bringing bacteria levels comparable to those of U.S. drinking water."