Bangladesh is underlain by shallow aquifers in which millions of drinking water wells are emplaced without annular seals. Fecal contamination has been widely detected in private tubewells. To evaluate the impact of well construction on microbial water quality 35 private tubewells (11 with intact cement platforms, 19 without) and 17 monitoring wells (11 with the annulus sealed with cement, six unsealed) were monitored for culturable Escherichia coli over 18 months. Additionally, two ‘snapshot’ sampling events were performed on a subset of wells during late-dry and early-wet seasons, wherein the fecal indicator bacteria (FIB) E. coli, Bacteroidales and the pathogenicity genes eltA (enterotoxigenic E. coli; ETEC), ipaH (Shigella) and 40/41 hexon (adenovirus) were detected using quantitative polymerase chain reaction (qPCR). No difference in E. coli detection frequency was found between tubewells with and without platforms. Unsealed private wells, however, contained culturable E. coli more frequently and higher concentrations of FIB than sealed monitoring wells (p < 0.05), suggestive of rapid downward flow along unsealed annuli. As a group the pathogens ETEC, Shigella and adenovirus were detected more frequently (10/22) during the wet season than the dry season (2/20). This suggests proper sealing of private tubewell annuli may lead to substantial improvements in microbial drinking water quality.
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Research Article|
October 25 2012
Unsealed tubewells lead to increased fecal contamination of drinking water
Peter S. K. Knappett;
1Department of Earth & Planetary Sciences, University of Tennessee, Knoxville, TN 37996-1410, USA
2Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964, USA
E-mail: [email protected]
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Larry D. McKay;
Larry D. McKay
1Department of Earth & Planetary Sciences, University of Tennessee, Knoxville, TN 37996-1410, USA
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Alice Layton;
Alice Layton
3Center for Environmental Biotechnology, University of Tennessee, Knoxville, TN 37996-1605, USA
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Daniel E. Williams;
Daniel E. Williams
3Center for Environmental Biotechnology, University of Tennessee, Knoxville, TN 37996-1605, USA
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Md. J. Alam;
Md. J. Alam
4Department of Geology, University of Dhaka, Dhaka 1000, Bangladesh
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Brian J. Mailloux;
Brian J. Mailloux
5Department of Environmental Science, Barnard College, New York, NY 10027, USA
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Andrew S. Ferguson;
Andrew S. Ferguson
6Civil Engineering & Engineering Mechanics, Columbia University, New York, NY 10027, USA
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Patricia J. Culligan;
Patricia J. Culligan
6Civil Engineering & Engineering Mechanics, Columbia University, New York, NY 10027, USA
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Marc L. Serre;
Marc L. Serre
7Department of Environmental Sciences & Engineering, University of North Carolina – Chapel Hill, USA
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Michael Emch;
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Michael Emch
8Department of Geography, University of North Carolina – Chapel Hill, USA and Carolina Population Center, University of North Carolina – Chapel Hill, USA
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Kazi M. Ahmed;
Kazi M. Ahmed
4Department of Geology, University of Dhaka, Dhaka 1000, Bangladesh
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Gary S. Sayler;
Gary S. Sayler
3Center for Environmental Biotechnology, University of Tennessee, Knoxville, TN 37996-1605, USA
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Alexander van Geen
Alexander van Geen
2Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964, USA
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J Water Health (2012) 10 (4): 565–578.
Article history
Received:
June 05 2012
Accepted:
September 09 2012
Citation
Peter S. K. Knappett, Larry D. McKay, Alice Layton, Daniel E. Williams, Md. J. Alam, Brian J. Mailloux, Andrew S. Ferguson, Patricia J. Culligan, Marc L. Serre, Michael Emch, Kazi M. Ahmed, Gary S. Sayler, Alexander van Geen; Unsealed tubewells lead to increased fecal contamination of drinking water. J Water Health 1 December 2012; 10 (4): 565–578. doi: https://doi.org/10.2166/wh.2012.102
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