AWWA WQTC56996

The Honolulu Board of Water Supply (HBWS) is the largest water utility in the state of Hawaii and chlorinates only 50% of its deep (600 feet) groundwater sources to provide 150 mgd of potable water. The water quality in the distribution system contains low to undetectable levels of chlorine but meets the Total Coliform Rule. However, the upcoming Groundwater Rule (GWR) recommends that groundwater sources be chlorinated to reach a 0.2 mg/l residual in the distribution system as a treatment process to disinfect contaminating pathogens. Guidance under the GWR indicate that water utilities may be granted a variance to this disinfection requirement if their groundwater sources are naturally protected and are not vulnerable to contamination with fecal matter. In a previous study, the groundwater sources used by HBWS were monitored for multiple fecal indicator microorganisms (total coliforms, fecal coliforms, E. coli, fecal streptococci, C. perfringens, FRNA coliphages). Since most of 79 groundwater samples did not contain these fecal indicator microorganisms, it was concluded that these groundwater sources are naturally protected from fecal matter. However, human enteric viruses are the most likely pathogen to contaminate groundwater and are known to survive longer and are transported more readily through the soil environment than fecal bacteria. The objective of this study was to analyze HBWS groundwater sources for human enteric viruses. The experimental design of this study was to process 200 gallons of groundwater and to analyze these samples for infectious human enteric viruses using the standard cell culture method as well as the integrated cell culture and polymerase chain reaction (ICC-PCR) method. A total of 45 groundwater sources were initially determined to be negative for human enteric viruses by cell culture method and by the standard ICC-PCR results. However, based on seeding poliovirus into mock samples, the standard ICC-PCR method was determined to be unreliable due to interferences from sample components. A modified ICC-PCR was developed to increase the sensitivity of the assay method. Using this modified method, 40 of the groundwater samples tested were shown to be negative for human enteric viruses. Two conclusions can be drawn from this study. First, that PCR methods must be optimized for each laboratory before they are used. Second, the absence of human enteric viruses in all groundwater samples by cell culture and by cell culture and PCR method indicate that the groundwater sources used by the HBWS are not vulnerable to contamination by human enteric viruses. Includes 16 references, tables, figure.

Product Details

Edition:

Vol. - No.

Published:

11/01/2002

Number of Pages:

16

File Size:

1 file , 260 KB