Development of a new approach for assessing water quality in drinking water distribution systems

Laura Y. Sifuentes, Daniel R. Quintanar, Kelly R. Bright

Research output: Chapter in Book/Report/Conference proceedingConference contribution


The amoebae Naegleria fowleri, Acanthamoeba spp., and Balamuthia mandrillaris are free-living organisms found in the environment in both water and soil. All of these organisms may be found in ground water, surface water, and even finished drinking water worldwide although the public health significance is unknown at this time. In a summer screening, 251 samples of finished chlorinated drinking water were collected from across a municipal potable distribution system. Physio/chemical parameters (chlorine residual, temperature, pH, turbidity and conductivity) were measured for all samples. In addition, all samples were assayed for the presence of live amoebae. Of these, 45 (17.9%) were positive, two of which were positive for N. fowleri samples using polymerase chain reaction (PCR) assay. These positive locations were scattered throughout the distribution system as single point positives. More interestingly, some positive samples were found in clusters within the potable distribution system, suggesting that multiple water sources, hydraulic characteristics and poor maintenance of the distribution system environment itself may be contributing to the presence of these pathogenic water-based organisms. In this study, live amoebae were found in distribution water with more than an adequate chlorine residual (∼0.8 mg/L). Microorganisms that are typically used to monitor microbial water quality such as coliforms and Escherichia coli would most likely not be found under these circumstances. Also, these water-based amoebae are not fecal in origin. Therefore, live amoebae may not only provide a better indication of the water-based microbial quality of water, but such clustering as observed could reveal areas with other potential problems within the distribution system (e.g., physical/mechanical problems, contamination of a particular source, poor maintenance of that section of the distribution system, multiple blended sources and hydraulic changes due to meeting demand). We believe that routinely monitoring the presence of live amoebae could be used as a complementary monitoring program to the total coliform rule monitoring program and perhaps increase the sensitivity and specificity of detecting the overall microbial quality in drinking water distribution. 2011

Original languageEnglish (US)
Title of host publicationWater Quality Technology Conference and Exposition 2011
StatePublished - 2011
EventWater Quality Technology Conference and Exposition 2011 - Phoenix, AZ, United States
Duration: Nov 13 2011Nov 17 2011

Publication series

NameWater Quality Technology Conference and Exposition 2011


OtherWater Quality Technology Conference and Exposition 2011
Country/TerritoryUnited States
CityPhoenix, AZ

ASJC Scopus subject areas

  • Management, Monitoring, Policy and Law
  • Water Science and Technology


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