Microbial contamination of drinking water from risky tubewells situated in different hydrological regions of Bangladesh

Abstract This study, conducted in 40 selected upazilas covering four hydrological regions of Bangladesh, aimed at determining the risk of selected shallow tubewells (depth  95  = 12%–30%), 54% (CI 95  = 43%–65%) and 58% (CI 95  = 46%–69%) of water samples collected from category-1 tubewells were contaminated by E. coli , FC, and TC respectively during the wet season. The number of category-1 tubewells having E.coli was highest in the north-west (n = 8) and north-central (n = 4) region during wet season and dry season respectively, while the level of E.coli contamination in tubewell water (number of CFU/100 ml of sample) was significantly higher in north-central region. However, the south-west region had the highest number of FC contaminated category-1 tubewells (n = 16 & n = 17; respectively during wet and dry season) and significantly a higher level of TC and FC in sampled Category-1 tubewells than north-west, north-central and south-east region, mainly during wet season. Multivariate regression analysis could identified some sanitary inspection indicators, such as tubewell within E.coli contamination. Construction of pit latrine in areas with high water table should be highly discouraged. Raised sealed pits or flush/pour flash to septic tank could be installed considering sanitary inspection criteria. Water should be treated before drinking.