An Assessment of the Presence of Escherichia coli in the roof-collected rainwater from some areas around Nairobi

Abstract

One of the sources of feacal contamination of rainwater harvested from roofs is wind-blown dust containing particulate matter from animal faeces, or through direct defecation. Since the primary habitat for Escherichia coli (E.coli) is the gastro-intestinal tract of mammals and birds (Atlas 1984), it\'s a good indictor of feacal contamination (Hazen, 1988). This study aimed to investigate the presence of E.coli. In rainwater samples collected from roofs in some areas around Nairobi, which have different levels of livestock density. Forty four of the 89 samples collected tested positive for the presence of E.coli from Ngong Division, which had a cattle density of 1446 per square Kilometre was, 55%, but it was not significantly different from both Kikuyu Division: cattle density of 166; both of which had 34% of the samples testing positive to E.coli (p=0.3094). It was concluded that rain water harvested from roofs for human consumption in the study area should be treated before use.