Definitions:

Action Level – The concentration of a contaminant, which, when exceeded, triggers treatment or
other requirements that a water system must follow

EPA – Acronym for U.S. Environmental Protection Agency

Maximum Contaminant Level (MCL) – Highest level of a contaminant allowed in drinking water.
MCL’s are set as close to the MCLG as feasible using the best available treatment technology.

Maximum Contaminant Level Goal ( MCLG) – Level of a contaminant in drinking water below
which there is no known or expected risk to health. MCLG’s allow for a margin of safety.

MFL – millifibers per liter

PPM – Milligram per liter or one part per million

PPB – microgram per liter or one part per billion

PCi/L – Picocuries per liter measures radioactivity in water. A picocurie is 10^-12 curies and is the
quantity of radioactive material producing 2.22 nuclear transformations per minute.