Abstract: Indicator organisms are commonly used to assess the quality of surface waters. Fecal coliforms (FC)
are the most commonly used bacterial indicator of fecal pollution. Total coliforms (TC) comprise bacterial
species of fecal origin as well as other bacterial groups. The coliforms are indicative of the general hygienic
quality of the water and potential risk of infectious diseases through water. High FC and TC counts in water are
usually manifested in the form of diarrhea, fever and other secondary complications. The present study revealed
that, the study area of the River Cauvery and Bhavani were grossly polluted in respect of coliform assessment
which is mainly attributed to the open defecation, high amount of raw sewage and barrage sedimentation.
Hence the water is not fit for drinking purposes due to higher coliforms counts, which require continuous
monitoring and proper disinfection made if the water is to be used for drinking purpose. The severely
contaminated stations of Rivers Cauvery and Bhavani with respect to total coliforms are Vairapalayam (1800
MPN/100ml) and Bhavani Sagar (920 MPN/100ml). This study revealed a high degree of variability in the fecal
and total coliforms in various stations of these rivers.