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As we saw in the wake of Hurricane Katrina in 2005, clean drinking water can be a premium. Wharton's website shows how a tampon can serve as a water-filtration system at the bottom of a cut-open water bottle. Make sure all the fibers of the tampon are exposed first, and then put it at the bottom of a cut-open bottle. After a few minutes, the results are pretty impressive, but the water still needs to be boiled and purified.