In rural areas, germs aren’t the only danger to drinking water; pollutants and pesticides can get into supplies too. But soak small segments of peel in a rubbing alcohol solution, dry them out, and put them in dirty groundwater for a couple of hours and they adsorb heavy metal ions, dyes, pesticides, and nanoparticles like gold and silver. Remove the peels and the water is ready to drink. While it doesn’t rid the H2O of pathogens, it provides cleaner water using biowaste already on hand.
http://www.wired.com/wiredscience/2013/12/purify-water-with-fruit-peels/