According to the USEPA drinking water regulations, failure of the public water system to comply with monitoring requirements requires notification to all customers within:

The correct choice is based on the guidelines established by the USEPA, which stipulate that if a public water system fails to comply with monitoring requirements, they are required to notify their customers within a specified timeline. Specifically, the regulation mandates that this notification must occur within 1 year of the failure. This time frame ensures that customers are adequately informed about the potential impacts on water quality and safety as a result of the non-compliance. The extended period allows water systems time to address the monitoring failures while still prioritizing consumer awareness and public health protections.

Understanding this requirement emphasizes the importance of transparency and communication between water systems and the communities they serve, reinforcing the responsible management of drinking water standards.