The presence of microorganisms and their potential impacts on drinking water from boreholes, bowsers, lakes, rivers, springs, taps and wells was investigated in peri-urban settlements around Harare. Escherichia coli, Salmonella sp., Vibrio cholerae and faecal streptococci were present in all water sources except for the boreholes and bowsers. Rivers, lake and wells showed the greatest diversity of 10, 5 and 6 species and relative density (rd) of 90.9, 83.4 and 61.67% respectively for the protozoan parasites. Cryptosporidium was identified in groundwater sources; wells (rd = 8.3%) and springs (rd = 41.7%) and identified in tap water (rd = 6.23%) and the Mukuvisi River downstream (rd = 8.3%). Entamoeba histolytica, Cyclospora, Isospora belli, Trichuris trichiura and Giardia lamblia were found in all water sources. Eggs/larvae of intestinal parasites; Ascaris lumbricoides, Strongyloides, Rhabditis, Taenia sp. and Schistosoma mansoni were identified in different water sources. Faecal coliform levels had a significant effect on the water sources' water quality with p = 0.018 in all sites except for the borehole whilst faecal streptococci had no significant impact with p = 0.513. The presence of at least one microbial pathogenic organism and parasites in most of the water sources poses a threat to the water quality and is a human health risk in the study areas.
Keywords: coliforms, drinking water, Harare, microorganisms, parasites, protozoa