What is the acceptable level of Total Coliform according to the Primary MCL guidelines?

The acceptable level of Total Coliform according to the Primary Maximum Contaminant Level (MCL) guidelines is designed to ensure safe drinking water by prohibiting the presence of coliform bacteria, which are indicators of potential contamination. The guidelines stipulate that a water system can have a maximum of one positive sample for total coliform in a month if the system collects fewer than 40 samples. However, if there are 40 or more samples taken during the month, no more than 5% of those samples can be positive for total coliform.

This approach balances safety with the practical capabilities of water testing and monitoring. Therefore, the correct answer encompasses both criteria: having no more than 1 positive sample for systems with fewer than 40 samples, and a maximum of 5% positive samples when testing exceeds that threshold. Thus, both conditions are effectively represented in the response, which is why selecting the option that includes both criteria is appropriate.