Coliform oarganisms are used as indicators of faecal pollution rather than the water borne pathogens because: Coliform organisms are constantly present in abundance in human intestine. They are easily detected by culture methods as small as one bacteria in 100 ml of water whereas other methods of detecting pathogens are complicated and time consuming. They survive longer than pathogens They have greater resistance to forces of natural purification than the water borne pathogens. Parks textbook of preventive and social medicine.K Park. Edition 23.Pg no: 721