What is the Secondary MCL for fluoride, which affects aesthetic quality?

The correct value for the Secondary Maximum Contaminant Level (MCL) for fluoride, which is set to address aesthetic concerns such as taste, odor, or color rather than health effects, is indeed 2 mg/l. This level is established by the U.S. Environmental Protection Agency (EPA) to ensure that drinking water maintains a pleasant experience for consumers.

Fluoride in higher concentrations can impart a bitter taste and may lead to other undesirable characteristics in water, which can discourage people from drinking it. While fluoride has benefits for dental health, the secondary MCL is designed to prevent aesthetic issues, rather than health risks.

In contrast, levels above this threshold could lead to complaints about the taste and overall quality of the water, which is why the secondary standards are important for public acceptance of drinking water sources.