If a water system exceeds a maximum contaminant level (MCL), who is responsible for correcting the issue?

When a water system exceeds a maximum contaminant level (MCL), the responsibility for correcting the issue primarily falls on the water supplier. The water supplier is tasked with ensuring that the water provided to consumers meets safety standards established by the authorities. This includes regularly testing water quality, implementing treatment strategies, and making necessary adjustments to ensure compliance with MCLs.

While other entities, such as the health department and environmental agencies, may provide oversight, guidance, and regulatory enforcement, it is the water supplier that operates the water system on a day-to-day basis. They are directly involved in any remedial actions, such as modifying treatment processes or notifying consumers about potential health risks, to bring the water quality back into compliance.

Local government may also play a role in support, especially if changes to infrastructure or funding are needed, but the primary obligation resides with the water supplier to ensure the safety and quality of the water they provide.