Abstract: An in-line water monitoring system for the detection of the accidental or intentional introduction of potentially harmful substances. The automated system comprises a water pressure driven concentration unit that filters drinking water through a hollow-fiber filter. Material collected on the filter is backflushed into a collection vessel by passing a sterile solution through the filter in the reverse direction. An electronic signal at the end of the backflush sequence triggers a sensor such as an array biosensor to begin processing and analyzing the sample. The array biosensor houses a slide prepared with antibodies to the test organism. The array biosensor is programmed to automatically run sample and detection reagents over the slide, analyze the resulting pattern for positive and negative data, and report the results.