Maximum contaminant level: the highest level of a contaminant that is allowed in drinking water. MCLs are set as close to the maximum contaminant level goals as feasible using the best available treatment technology.
Maximum contaminant level goal: the level of a contaminant in drinking water below which there is no known or expected risk to health. MCLGs allow for a margin of safety.
Treatment technique: a required process intended to reduce the level of a contaminant in drinking water.
Action level: the concentration of a contaminant which, if exceeded, triggers treatment or other requirements which a water system must follow.
Variances and Exemptions:
State or EPA permission not to meet an MCL or a treatment technique under certain conditions.
Maximum residual disinfection level goal. The level or a drinking water disinfectant below which there is no known or expected risk to health. MRDLGs do not reflect the benefits of the use of disinfectants to control microbial contaminants.
Maximum residual disinfectant level. The highest level of a disinfectant allowed in drinking water. There is convincing evidence that addition of a disinfectant is necessary for control of microbial contaminants.
Monitored not regulated.
State assigned maximum permissible level.