The maximum level of a contaminant allowed in water by federal law. Based on health effects and currently available treatment methods. The MCL process starts with an assessment of the detrimental effects brought by certain chemicals and the required doses that causes these effects. The assessment has various requirements for compliance that is based on the contaminants found in the water and the kind of health concerns it raises, including environmental risks. The usual margin of safety for MLC’s is between 10 - 1000 for the purposes of ensuring all health issues are anticipated and prevented.