VIRUSES IN GROUND WATER

May 18, 2006

Madison—As a result of the findings of a recently completed research project, presented yesterday at the Madison Board of Water Commissioners meeting, Utility staff today have reviewed the chlorine levels at each of its 24 wells and recalculated the effectiveness of those chlorine levels to ensure that the chlorine levels in the entire drinking water system are sufficient to kill any viruses that could be in the system.

There is always a possibility that viruses and bacteria can find its way into the drinking water system in the distribution lines or in home plumbing systems, and the Utility always maintains a chlorine level in the water designed to disinfect and kill any such microbial organisms.

Madison Water Utility provided access to deep ground water samples from three of its well for this research, conducted, over the last two years, by Dr.Ken Bradbury, Hydrologist, Wisconsin Geological and Natural History Survey and Dr. Mark Borchardt, Director of Public Health, Microbiology Laboratory, Marshfield Clinic Research Foundation. The researchers found viruses in two of the three wells sampled. All viruses were found in samples from raw water, before it was chlorinated by the Utility and placed into the distribution system.

The surprising findings of the research project reported yesterday, was the location where the viruses were found. The viruses were found in samples taken from the deep ground water aquifer. The researchers, themselves, were surprised by the findings in that previous scientific assumptions were that such viruses would not be found in deep ground water aquifers.

The Utility today reviewed the recommended chlorine levels for the types of viruses found, and concluded that there is sufficient chlorine being added at all of its wells to kill these viruses. The Utility increased the chlorine level slightly at one well as a result of its review.

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Contact:
  • David Denig-Chakroff, (608) 266-4652