What is the maximum contaminant level for arsenic in drinking water?

The maximum contaminant level (MCL) for arsenic in drinking water is set at a specific concentration to ensure public health safety, and it is indeed higher than what is considered technically feasible in certain treatment processes. The U.S. Environmental Protection Agency (EPA) has established the MCL for arsenic at 0.010 milligrams per liter (10 parts per billion). This regulatory threshold is based on weighing both health risks and the capabilities of water treatment technology to effectively reduce arsenic levels.

While technically feasible treatment options may exist to reduce arsenic concentration effectively, the maximum allowable level has been set to balance technological capabilities with health protection goals. Therefore, the MCL exceeds the levels which might be technically achievable under ideal circumstances where contamination is dealt with in the most efficient ways. Thus, B captures the relationship between the MCL and the technically feasible level by indicating that the regulatory limit is set higher than the level that might be practically achievable at all times during treatment operations.