What is the maximum contaminant level (MCL) for nitrate in drinking water?

The maximum contaminant level (MCL) for nitrate in drinking water is established at 10 milligrams per liter. This standard is set by regulatory agencies to protect public health because elevated levels of nitrate can lead to serious health issues, particularly for infants and pregnant women, as they can impede oxygen transport in the blood, a condition known as methemoglobinemia or "blue baby syndrome."

The MCL represents an acceptable level of a contaminant in drinking water that is not expected to pose a significant risk to human health. It's important for water operators to regularly test for nitrate levels and ensure they do not exceed this limit to safeguard against potential health risks associated with nitrate exposure. Other listed levels, such as 5, 15, and 20 milligrams per liter, do not conform to the established standard and may imply increased risk to health if they were accepted as MCLs.