Cover of Reevaluation of Microbial Water Quality: Powerful New Tools for Detection and Risk Assessment
In the dead of night, a storm rumbles across farmlands and cow pastures; torrents of rain drench the earth. Of the hundreds of cows that graze in the saturated fields, several harbor E. coli O157:H7, a bacterium harmless to livestock but potentially deadly to people. The bacterium, shed in the cows’ manure, is washed into a stream that feeds a public water district 20 miles away.

Hours later, a red light flashes on an electronic watershed map mounted on the control panel of the water district’s monitoring station. Microbial contaminants—detected by gene chips affixed to stationary stream posts (or implanted in the gills of fish sentinels) and inserted into wells—have entered the system. Other lights flash, indicating the identity of the microbe. The lights alert the district water manager. She tracks the contaminants. Noting that virulent E. coli bacteria are moving into the town’s shallow well system located at the river banks, she ratchets up the chlorination, and then contacts the regional health manager who issues a boil water order. The next morning, local TV and radio stations issue the warning, and local citizens, especially those with young children, hospitals and the elderly are all alerted. A possible E. coli outbreak is averted. The new water quality monitoring system has passed a rigorous test. Nature designed the test. The water district and the residents of the town knew it would come, they just didn’t know when or where.

In this scene from the future, gene chip technology identifies a target microorganism and registers its presence in real time through telemetry. The miniature chip contains "capture genes," genetic sequences specific to dozens of different pathogenic microorganisms. When the target genetic material contacts the chip, it produces an electronic signal alerting the water management facility. The chip is just one of a number of technologies being developed in universities and laboratories around the country to assure water quality. When these technologies are available, they will save lives and prevent illness caused by waterborne disease. For now, however, water quality monitoring is mired in the past. This past has served the public well, but it is time to move ahead to better protect public health.


Joan B. Rose, D. Jay Grimes. 2001. Reevaluation of microbial water quality: powerful new tools for detection and risk assessment.

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