When people make improvised explosive devices (IEDs), many of the waste products end up simply going down the drain. With that in mind, the European Union-funded EMPHASIS consortium is now developing technology to track those chemicals within the waste stream, so that their point of origin can be located.

Here's how the EMPHASIS system would work ...

A network of electrochemical water-sampling sensors would be placed at regular intervals within a municipal sewer system, along with above-ground air-sampling sensors. When any of these devices detected suspicious concentrations of water- or airborne compounds used in the building of IEDs, an alert would be sent to a central command center.

Personnel at that center would note the general location of the reporting sensors, then remotely access additional sensors in that same area, in order to narrow down the possible originating points of those chemicals. From there, mobile field units would be sent out to the vicinity, using portable sensing equipment to pinpoint the bomb-makers' exact location.

The system could conceivably also be used to find meth labs, or other locations where illicit drugs were being synthesized.

According to a report in New Scientist, the water-sampling sensors have already been tested in "feces-rich" water in a lab setting, with plans calling for testing in real sewers to take place next year.