Unsealed tubewells lead to increased fecal contamination of drinking water

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, 6 unsealed) were monitored for cultured E. coli over 18 months. Additionally, two “snap shot” 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 (ETEC E. coli), ipaH (Shigella) and 40/41 hexon (adenovirus) were detected using qPCR. No difference in E. coli detection frequency was found between tubewells with and without platforms. Unsealed private wells, however, contained cultured E. coli more frequently and higher concentrations of FIB than sealed monitoring wells (p