On Sept. 11, 2001, water resource managers across the United States got a wake-up call. In addition to desalinization projects and efforts to remove industrial waste, they now faced the possibility of intentional acts of poisoning public water. Sandia National Laboratories thinks it can help. To head off terrorist attacks on U.S. drinking water, Sandia has adapted its lab-on-a-chip, called the MicroChemLab, to real-time monitoring of public waterworks. The device aims to give water resource managers a real-time readout not only of poisons, but also of the naturally occurring toxins for which waterworks can now sample only randomly. The microfluidic-chip-based MicroChemLab prototype, fabricated with microelectromechanical systems, today resembles a 25-pound suitcase with two water collectors protruding from it. It is currently being tested in the Contra Costa Water District in California, collecting and analyzing water samples every 30 minutes and reporting the results in real-time over a wired link to researchers at Sandia. If testing is successful, future production versions of the MicroChemLab will be eligible for installation in any of the more than 300,000 U.S. public-supply water wells, 55,000 utilities and 120,000 rest stops and campgrounds.