What is the action level for copper in drinking water?

The action level for copper in drinking water is established at 1.3 mg/l. This standard is part of the Environmental Protection Agency's (EPA) regulations under the Lead and Copper Rule, which aims to minimize the presence of copper and lead in drinking water due to potential health risks.

Copper, while it is an essential nutrient for human health in small amounts, can lead to adverse health effects such as gastrointestinal distress and liver damage when present in excessive quantities. The action level is not a maximum contaminant level but rather a threshold that, if exceeded in more than 10% of tap water samples taken at consumer taps during a monitoring period, triggers certain actions by the water supplier, such as installation of corrosion control treatment or public education efforts.

The other choices presented do not align with the federal standard set for copper levels. Water operators must be vigilant in monitoring and maintaining levels below this action level to ensure the safety and health of the drinking water supply.