With the objective of better defining the presence of coliform bacteria and E. coli in
drinking water distribution systems, a sample collection and analysis method was developed to
allow determination of the presence of these water quality indicators in volumes greater than the
conventional 100 mL sample. Bench studies indicated the resulting method was capable of
consistent detection of the presence of total coliforms and E. coli when challenged with test
water seeded to E. coli concentrations of as low as 0.025 cfu per 100 mL, and from sample
volumes as large as 20 L. Field trials in water distribution systems were then performed at three
participating utilities, at each of which as many as one hundred 20 L samples were collected and
analyzed by the new method as well with the 100 mL method. In the 240 total sample sets, the
20 L method found total coliform to be present in 18 samples, but in only two of these were the
corresponding 100 mL samples total coliform positive. E. coli was not detected by either sample
volume at any location. The results indicate that distribution water quality may be better
characterized using this high volume method, and confirm the hypothesis that the presence of
total coliform positives is a function of sample volume rather than being an indicator of distribution
system water quality. Includes 12 references, tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 800 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 14 |
| Published : | 11/01/2008 |
