Ensuring clean water, 1 page at a time. A scientist at Carnegie Mellon University in Pittsburgh has created a book that can provide its owner with drinkable water for up to 4 years.

As the Telegraph reports, Dr. Theresa Dankovich has created a book with pages that tear out and turn easily into water filters. Thanks to nano-particles of copper and silver, the page removes at least 99% of the water’s contaminants, making it safe enough to qualify for US drinking standards.

During tests in South Africa, Ghana, and Bangladesh, the book performed admirably, filtering even raw sewage to the point where it would be considered safe to drink. Just 1 page can be used to filter up to 100 liters of water before losing its effectiveness.

The resulting water shows slight traces of “leeched” copper and silver, but so far the levels are well within safe range. Users may consider it a fair trade considering the paper has killed nearly all bacteria in all tests.

“It’s directed towards communities in developing countries,” Dr. Dankovich said. “It’s really exciting to see that not only can this paper work in lab models, but it has also shown success with real water sources that people are using.”

The next step includes speeding production of the books, which are currently made by hand. Then, hopefully, increasing trials in some of the areas where the nearly 663 million people reside without access to clean drinking water.