The researchers developed crystals as small as 12 nanometers wide using nanotechnology. These crystals then were mixed with contaminated water. After some time, they found that the crystals were coated with arsenic and were acting like iron filings; the contaminants then were removed with the help of a strong magnet. When the water was tested, it was found to be well within the international safety limits.

Professor Doug Natelson, one of the authors of the report, says that the trick was not new and was being practiced by chemical engineers for years, adding that the team was surprised to see that the particles could be removed by using hand-held magnets in some of the cases.

"The trick here is that these particles are very, very small, which means they're essentially all surface. So the arsenic sticks to the surface of the particles, and what we've found is that when the nanoparticles are in the right range of sizes, you can pull them out of solution with a relatively small magnetic field gradient that you could get from, say, a permanent magnet," he explains.

Professor Natelson notes that this technology, if proved, would be like a boon for many countries where drinking water, contaminated with arsenic, is posing a grave problem. "You'd have little packets that had this powder in it, you'd fill up your pitcher of water, you'd dump in the powder, stir it up, let it sit for a little bit, and then you'd have a permanent magnet that draws all the minerals down towards the bottom of the pot, and then you pour off the relatively clean water,” he adds.