Classical indicators in the 21st century--far and beyond the coliform

Area of Science:

• Environmental microbiology
• Public health science
• Water quality monitoring

Background:

• Microbiological indicators have been crucial for assessing water quality for decades.
• Early standards, like the 1914 U.S. Public Health Service standard, focused on coliform organisms.
• Current regulations, such as the Total Coliform Rule, continue to rely on total coliform bacteria as a key indicator.

Purpose of the Study:

• To review the historical use of indicator microorganisms in water quality assessment.
• To highlight the limitations of traditional coliform-based indicators.
• To discuss the emergence and adoption of new microbial indicators for specific water safety applications.

Main Methods:

• Literature review of historical water quality standards and regulations.
• Analysis of the evolving scientific understanding of microbial indicators.
• Synthesis of information from recent reports by authoritative bodies like the National Research Council and World Health Organization.

Main Results:

• The use of coliforms as sole indicators of water quality has limitations.
• Expanding applications and scientific understanding have driven the need for new indicators.
• Several new indicators have been proposed and adopted for specific water safety purposes.

Conclusions:

• The reliance on total coliforms for water quality assessment is being re-evaluated.
• Newer indicator microorganisms offer improved specificity and broader applications.
• The field is moving towards a more nuanced approach to microbiological water safety monitoring.