Which regulation governs microbial monitoring in drinking water distribution systems?

• A. Interim Enhanced Surface Water Treatment Rule
• B. Surface Water Treatment Rule
• C. Total Coliform Rule
• D. Filter Backwash Recycle Rule

Answer: (C)

The regulation that governs microbial monitoring in drinking water distribution systems is the Total Coliform Rule. This rule uses the presence of total coliform bacteria as an indicator of potential microbial intrusion into the distribution system and sets the requirements for how often samples must be collected, what steps to take if coliforms are detected (such as repeat sampling and corrective actions), and how results must be reported and tracked. It focuses specifically on monitoring in the distribution system to ensure ongoing water safety as it travels to consumers.

The other regulations address different aspects of drinking water management: the Interim Enhanced Surface Water Treatment Rule and the Surface Water Treatment Rule focus on treatment processes at the treatment plant, particularly for surface water sources, rather than distribution-system monitoring; the Filter Backwash Recycling Rule deals with the management of backwash water from filtration operations, not with microbial monitoring in the distribution system.