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National Source Water (Untreated) Levels of Virus
SEPTEMBER 1997



REMINDER: Data Purpose: The ICR data were collected as part of a national research project to support development of national drinking water standards. They should NOT be used to determine local water systems compliance with drinking water standards, nor should they be used to make personal judgements about health risks.

Results of Zero: A measurement of zero means that no Virus was found in the sample volume that was analyzed. Zero results do not indicate the absence of Virus in the source water because the method recovery is low and the amount of sample analyzed is small. In other words, Virus may be present in source water even if no virus are counted for the sample volume analyzed.

Efforts Beyond Regulations: Many large public water systems are voluntarily improving the control of pathogens by participating in the Pa rtnership for Safe Water, an initiative between EPA, the States, and water suppliers to improve the performance of treatment.


Percent Treatment Plants Reporting a Positive Occurrence of Virus

* A measurement result of zero means that no virus was found in the volume of water analyzed.


National Source Water (Untreated) Levels of Virus for SEPTEMBER 1997

National Source Water (Untreated) Levels of Virus for SEPTEMBER 1997

Level of Total Virus (MPN/100L) Number of Water Treatment Plants
0 163
1-9 39
10-99 7
100-999 1

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