Explain the Coliforms - Microbiological Study of Water?

These are widely used indicators which belongs to the family Enterobacteriaceae and make up about 10% of the intestinal microflora of human and other animals. These are facultative anaerobes, gram negatives, non sporing rods that ferment lactose with gas formation within 48 hours at 35°C. These include E.coli, Enterobacter aerogenes and Klebsiella pneumoniae. Absence of these in water sample indicates the absence of faecal contamination and thus makes the water suitable for human consumption.