Hugh Pickens writes "Although most Americans take the safety of their drinking water for granted, ordinary tap water can become contaminated within minutes, says Prof. Abraham Katzir of Tel Aviv University's School of Physics and Astronomy who has developed a fiber-optic system that can detect poisons such as pesticides in water in amounts well below the World Health Organization safety threshold using 'colors' in the infrared spectrum which distinguish between pure and contaminated water. 'With our naked eyes we can't distinguish between pure water and water that contains a small amount of alcohol or acetone. They're all clear,' says Katzir. 'But we can clearly distinguish between liquids using an infrared spectrometer which can distinguish between "colors" in the invisible infrared spectrum.' Connected to a commercial infrared spectrometer, the fibers serve as sensors that can detect and notify authorities immediately if a contaminant has entered a water reservoir, system, building or pipeline. 'Toxic materials are readily available as pesticides or herbicides in the agriculture industry, and can be harmful if consumed even in concentrations as low as few parts per million,' says Katzir. Cities like New York are especially susceptible to a chemoterrorist threat. With many skyscrapers holding water reserves on the top of the building, a terrorist only needs to introduce poison into a tank to wreak havoc. 'A terrorist wouldn't have to kill tens of thousands of people. Only 50 deaths — as horrible as that would be — would cause nationwide panic,' says Katzir."