title: Can Sanitary Inspection Surveys Predict Risk of Microbiological Contamination of Groundwater Sources? Evidence from Shallow Tubewells in Rural Bangladesh.
abstract: Accurately assessing the microbiological safety of water sources is essential to reduce waterborne fecal exposures and track progress toward global targets of safe water access. Sanitary inspections are a recommended tool to assess water safety. We collected 1,684 water samples from 902 shallow tubewells in rural Bangladesh and conducted sanitary surveys to assess whether sanitary risk scores could predict water quality, as measured byEscherichia coli. We detectedE. coliin 41% of tubewells, mostly at low concentrations. Based on sanitary scores, 31% of wells were low risk, 45% medium risk, and 25% high or very high risk. Older wells had higher risk scores.Escherichia colilevels were higher in wells where the platform was cracked or broken (Δlog10= 0.09, 0.00-0.18) or undercut by erosion (Δlog10= 0.13, 0.01-0.24). However, the positive predictive value of these risk factors forE. colipresence was low (< 50%). Latrine presence within 10 m was not associated with water quality during the wet season but was associated with less frequentE. colidetection during the dry season (relative risk = 0.72, 0.59-0.88). Sanitary scores were not associated withE. colipresence or concentration. These findings indicate that observed characteristics of a tubewell, as measured by sanitary inspections in their current form, do not sufficiently characterize microbiological water quality, as measured byE. coli. Assessments of local groundwater and geological conditions and improved water quality indicators may reveal more clear relationships. Our findings also suggest that the dominant contamination route for shallow groundwater sources is short-circuiting at the wellhead rather than subsurface transport.
authors.affiliation: Division of Epidemiology, School of Public Health, University of California, Berkeley, California.
authors.forename: Ayse
authors.initials: A
authors.lastname: Ercumen
authors.affiliation: Rollins School of Public Health, Emory University, Atlanta, Georgia.|International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh.
authors.forename: Abu Mohd
authors.initials: AM
authors.lastname: Naser
authors.affiliation: Division of Epidemiology, School of Public Health, University of California, Berkeley, California.
authors.forename: Benjamin F
authors.initials: BF
authors.lastname: Arnold
authors.affiliation: International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh.
authors.forename: Leanne
authors.initials: L
authors.lastname: Unicomb
authors.affiliation: Division of Epidemiology, School of Public Health, University of California, Berkeley, California.
authors.forename: John M
authors.initials: JM
authors.lastname: Colford
authors.affiliation: Centers for Disease Control and Prevention, Atlanta, Georgia.|School of Medicine, Stanford University, Stanford, California.|International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh.
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Luby
mesh_terms: D001459:Bangladesh; D015169:Colony Count, Microbial; D060766:Drinking Water / Q000382:microbiology; D004784:Environmental Monitoring; D004926:Escherichia coli / Q000302:isolation & purification; D005243:Feces / Q000382:microbiology; D005506:Food Contamination; D005513:Food Inspection / Q000592:standards*; D005516:Food Microbiology; D060587:Groundwater / Q000382:microbiology*; D012307:Risk Factors; D012424:Rural Population; D012621:Seasons; D011795:Surveys and Questionnaires; D014871:Water Microbiology; D060753:Water Quality / Q000592:standards*; D060986:Water Wells
chemical_list: D060766:Drinking Water