Full Description

With the objective of better defining the presence of coliform bacteria and E. coli indrinking water distribution systems, a sample collection and analysis method was developed toallow determination of the presence of these water quality indicators in volumes greater than theconventional 100 mL sample. Bench studies indicated the resulting method was capable ofconsistent detection of the presence of total coliforms and E. coli when challenged with testwater seeded to E. coli concentrations of as low as 0.025 cfu per 100 mL, and from samplevolumes as large as 20 L. Field trials in water distribution systems were then performed at threeparticipating utilities, at each of which as many as one hundred 20 L samples were collected andanalyzed by the new method as well with the 100 mL method. In the 240 total sample sets, the20 L method found total coliform to be present in 18 samples, but in only two of these were thecorresponding 100 mL samples total coliform positive. E. coli was not detected by either samplevolume at any location. The results indicate that distribution water quality may be bettercharacterized using this high volume method, and confirm the hypothesis that the presence oftotal coliform positives is a function of sample volume rather than being an indicator of distributionsystem water quality. Includes 12 references, tables, figures.

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Edition: Vol. - No. Published: 11/01/2008 Number of Pages: 14File Size: 1 file , 800 KB