title: Water quality at points-of-use in the Galapagos Islands.
abstract: Piped drinking water is often considered a gold standard for protecting public health but research is needed to explicitly evaluate the effect of centralized treatment systems on water quality in developing world settings. This study examined the effect of a new drinking water treatment plant (DWTP) on microbial drinking water quality at the point-of-use on San Cristobal Island, Galapagos using fecal indicator bacteria total coliforms and Escherichia coli. Samples were collected during six collection periods before and after operation of the DWTP began from the freshwater sources (n=4), the finished water (n=6), and 50 sites throughout the distribution system (n=287). This study found that there was a significant decrease in contamination by total coliforms (two orders of magnitude) and E. coli (one order of magnitude) after DWTP operation began (p<0.001). However, during at least one post-construction collection cycle, total coliforms and E. coli were still found at 66% and 28% of points-of-use (n=50), respectively. During the final collection period, conventional methods were augmented with human-specific Bacteroides assays - validated herein - with the goal of elucidating possible microbial contamination sources. Results show that E. coli contamination was not predictive of contamination by human wastes and suggests that observed indicator bacteria contamination may have environmental origins. Together these findings highlight the necessity of a holistic approach to drinking water infrastructure improvements in order to deliver high quality water through to the point-of-use.
authors.affiliation: Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina, 170 Rosenau Hall, CB #7400, 135 Dauer Drive, 27599-7400 Chapel Hill, NC, USA. Electronic address: billy.gerhard@duke.edu.
authors.forename: William A
authors.initials: WA
authors.lastname: Gerhard
authors.affiliation: Department of Biostatistics, Gillings School of Global Public Health, University of North Carolina, 170 Rosenau Hall, CB #7400, 135 Dauer Drive, 27599-7400 Chapel Hill, NC, USA. Electronic address: choiwan@live.unc.edu.
authors.forename: Wan Suk
authors.initials: WS
authors.lastname: Choi
authors.affiliation: Department of Anthropology, University of North Carolina, 301 Alumni Building, CB #3115, UNC-CH, 27599-3115 Chapel Hill, NC, USA. Electronic address: khouck@live.unc.edu.
authors.forename: Kelly M
authors.initials: KM
authors.lastname: Houck
authors.affiliation: Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina, 170 Rosenau Hall, CB #7400, 135 Dauer Drive, 27599-7400 Chapel Hill, NC, USA. Electronic address: jill.stewart@unc.edu.
authors.forename: Jill R
authors.initials: JR
authors.lastname: Stewart
mesh_terms: D058491:Bacterial Load; D004269:DNA, Bacterial / Q000032:analysis; D060766:Drinking Water / Q000382:microbiology*; D004484:Ecuador; D004755:Enterobacteriaceae / Q000235:genetics / Q000302:isolation & purification*; D004784:Environmental Monitoring; D005243:Feces / Q000382:microbiology; D006801:Humans; D014871:Water Microbiology; D014873:Water Pollutants / Q000302:isolation & purification*; D060753:Water Quality; D014881:Water Supply
chemical_list: D004269:DNA, Bacterial; D060766:Drinking Water; D014873:Water Pollutants
keywords: Bacteroides; Escherichia coli; Fecal coliforms; Microbial source tracking; Post distribution contamination; Regrowth