What does the Total Coliform Rule require in routine distribution samples?

What does the Total Coliform Rule require in routine distribution samples?

• A. 2 positive coliforms allowed per month
• B. 1 positive coliform allowed in any sample
• C. No positive coliforms required
• D. 0 positive coliforms in routine distribution samples

Answer: (D)

Total coliforms serve as an indicator of the distribution system’s integrity. In routine distribution samples, their presence signals potential contamination and triggers immediate investigation and corrective action. Because of this, the rule requires that no positive total coliforms be detected in routine distribution samples—zero positives. A positive result would prompt repeat sampling, verification of sample collection quality, and possible actions like flushing, checking disinfection levels, and enhanced monitoring. The other options suggest allowing one or more positives, which would not align with the requirement to safeguard distribution reliability.

Total coliforms serve as an indicator of the distribution system’s integrity. In routine distribution samples, their presence signals potential contamination and triggers immediate investigation and corrective action. Because of this, the rule requires that no positive total coliforms be detected in routine distribution samples—zero positives. A positive result would prompt repeat sampling, verification of sample collection quality, and possible actions like flushing, checking disinfection levels, and enhanced monitoring. The other options suggest allowing one or more positives, which would not align with the requirement to safeguard distribution reliability.