Huria: Journal of the Open University of Tanzania

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The microbiological quality of wells and borehole waters in Dar es Salaam Region.

PP Orotho, WT Fweja


The present study was carried out to examine the microbiological quality of 45 randomly selected wells and boreholes in Dar es Salaam City. Total coliform and fecal coliforms were used as indicator microorganisms. Coliform count was done by using a three tube assay of Most Probable Number (MPN) technique in which both Presumptive coliform test and Confirmation test were carried out. Questionnaire and observational methods were used to collect information on the possible sources of contamination and the construction and maintenance of well/ boreholes. The results generally indicate poor water quality with an overall mean values of 424 and 379 cfu/100 ml for total caliform and feacal caliform (for Temeke Municipality), 5 and 8 cfu/100ml for total and feacal califorms respectively (for Ilala Municipality) and 175 and 113 cfu/100 ml for total and feacal califorms respectively (for Kinondoni Municipal). Toilets, septic tanks and poor construction and maintenance of wells and boreholes were identified as the possible potential sources of contamination of the well and borehole waters. The majority of the wells and boreholes were within 10 to 20m from toilets and septic tanks while the WHO guideline recommends 30m away from latrine and 17m from septic tanks. On the other hand, most of them were not protected and lacked concrete floor around the dug well. Records on the depth of boreholes and wells showed that the majority of the water sources had a depth of over 50m and very few had depth of <20m and between 20-30m.

Keywords: Boreholes, well, total coliform, feacal coliform

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