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Giardia and Cryptosporidium have emerged as waterborne pathogens of concern over the past few decades. Twenty-nine source water samples were collected from water treatment facilities and checked for the occurrence of Giardia and Cryptosporidium along with some water quality parameters. These facilities include ten large-scale treatment plants near major metropolitan areas, and eight simple facilities in small and secluded communities. The indirect immunofluorescence assay (IFA) was used for the detection of cysts and oocysts in water samples. In addition, fecal specimens were collected from watersheds providing source water for the treatment plants, and the presence of Giardia and Cryptosporidium was detected with the enzyme-linked immunosorbent assay (EIA). The mean concentrations of protozoa in large-scale plants were 66.6 cysts/100 litres and 89.2 oocysts/100 litres, whilesimple facilities contained 1.27 cysts/100 litres and 0.28 oocysts/100 litres, respectively. The concentrations of these two parasites exhibit the highest correlation with turbidity than any other water quality parameters. Amongthe 101 fecal specimens, eleven were positive for Giardia and 22 were positive for Cryptosporidium. It was also found that the occurrence of these two pathogens in the source water was directly linked to the surrounding farming activities, suggesting that farming activities should be kept at a certain distance from the watersheds.

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