Why are Escherichia coli and coliforms used as indicator organisms?
The coliform group nearly fulfills the criteria listed above. Escherichia coli is considered a reliable indicator of bacterial pathogens. Protozoans and viruses, however, usually survive longer than E. coli and may also survive disinfection that is otherwise adequate for bacteria. Filtration is usually successful in extracting protozoans and viruses and should be used in conjunction with disinfection procedures. Source: University of Waterloo. Environmental Microbiology 447. “Module 4. Pathogens in Water” Canada. 10/7/2002.
