What is the primary difference between MCL and SMCL?

The primary difference between MCL and SMCL lies in the focus of each standard. Maximum Contaminant Levels (MCLs) are regulatory limits set for contaminants in drinking water based on health considerations. These levels are established to protect public health by ensuring that drinking water does not contain harmful substances that could pose risks to human health.

On the other hand, Secondary Maximum Contaminant Levels (SMCLs) are guidelines set for contaminants that primarily affect the aesthetic qualities of drinking water, such as taste, odor, and color. These do not pose health risks but can affect the acceptability of the water by consumers.

Understanding the significance between these two is essential for water distribution operators, as they need to ensure that both health-related contaminants are below MCLs and that any aesthetic issues related to SMCLs are addressed to maintain public confidence in the water supply.