The secondary standard for manganese recommends that the concentrations not exceed:

Manganese is an essential element for human health in small amounts, but elevated concentrations can lead to health risks, including neurological issues and other health effects. The secondary standards established by the U.S. Environmental Protection Agency (EPA) focus primarily on aesthetic qualities, including color, taste, and odor, rather than direct health impacts, although they can have indirect health consequences.

The recommended concentration for manganese not to exceed is aligned with the goal of maintaining water quality that is acceptable for consumption. A concentration of 0.05 mg/L ensures that manganese levels in drinking water remain within a range that minimizes the risks of adverse effects while also preventing unpleasant taste or staining of laundry and fixtures.

This threshold has been established based on extensive studies and observations regarding the impact of manganese at higher levels, reinforcing the importance of controlling manganese concentration in public water supplies to safeguard the health and well-being of consumers. Therefore, the choice of 0.05 mg/L accurately reflects these considerations and is recognized as the appropriate standard for manganese in drinking water.