Which organism is commonly used as an indicator of water safety?

E. coli, specifically certain strains known as non-pathogenic E. coli, is commonly used as an indicator organism for water safety. This bacterium is part of the normal intestinal flora in humans and other warm-blooded animals, and its presence in water indicates fecal contamination. Since E. coli is generally harmless in its non-pathogenic forms, it serves as a reliable indicator without posing significant risks to health directly.

Monitoring for E. coli in water supplies helps assess the effectiveness of water treatment processes and the potential presence of pathogenic microorganisms. If E. coli is detected, it suggests that contamination with fecal matter has occurred, which may also involve more harmful pathogens that can cause serious diseases in the population.

This choice is preferable in water safety assessments because the presence of E. coli correlates with increased risks of disease outbreaks from enteric pathogens, thus making it a standard for evaluating water quality and safety practices.