When a total coliform-positive sample is detected, which action is recommended?

When a total coliform-positive sample is detected, which action is recommended?

• A. Repeat sampling at the original and nearby sites and consider shock chlorination
• B. Immediately boil-water notice
• C. No action is required
• D. Close the plant for the day

Answer: (D)

When total coliforms are detected, the priority is to protect public health by stopping distribution and beginning an immediate investigation of the system. Closing the plant for the day is a decisive step that prevents any potentially unsafe water from leaving the facility while you collect repeat samples, assess the source of contamination, perform flushing, and implement corrective actions such as shock chlorination and proper disinfection before resuming operations. Repeating sampling and considering shock chlorination are important parts of the remediation plan, but they follow the decision to halt production to prevent exposure. A boil-water notice is a protective action used in higher-risk scenarios or after confirmation of fecal contamination, and may follow the initial investigation, not serve as the immediate response to a total coliform-positive result. No action is not acceptable because the finding signals a possible contamination pathway that needs prompt attention.

When total coliforms are detected, the priority is to protect public health by stopping distribution and beginning an immediate investigation of the system. Closing the plant for the day is a decisive step that prevents any potentially unsafe water from leaving the facility while you collect repeat samples, assess the source of contamination, perform flushing, and implement corrective actions such as shock chlorination and proper disinfection before resuming operations. Repeating sampling and considering shock chlorination are important parts of the remediation plan, but they follow the decision to halt production to prevent exposure. A boil-water notice is a protective action used in higher-risk scenarios or after confirmation of fecal contamination, and may follow the initial investigation, not serve as the immediate response to a total coliform-positive result. No action is not acceptable because the finding signals a possible contamination pathway that needs prompt attention.