Which of the following indicates a violation under the Total Coliform Rule?

The Total Coliform Rule is designed to protect public health by ensuring that water systems are monitored for coliform bacteria, which can indicate contamination. A situation that clearly indicates a violation of this rule is when a repeat sample shows the presence of total coliform (denoted as TC+) or when a required sample is missed altogether.

When a routine sample tests positive for total coliform, the water system is required to take repeat samples to assess whether the contamination is persistent. If any of those repeat samples also return positive for total coliform or if a sample that should have been collected is not, it signifies a failure to maintain safe water quality standards. This scenario demonstrates that the system is not effectively managing the risk of bacterial contamination, therefore constituting a violation.

When considering the other options, missing just routine samples alone does not necessarily indicate a violation of the Total Coliform Rule, as there are often provisions for missing a certain number of samples without immediate consequence. A single TC+ sample might not be a violation unless it is followed by inadequate follow-up actions. Collecting samples from different sites in the same day is not inherently a violation, as long as the sampling process adheres to the regulatory requirements and does not compromise the integrity of the samples taken.