MCL is an abbreviation for Maximum Contaminant Level. These are the guidelines set by the EPA and State and local Health Departments in order to protect human health. Any regulated parameter has an MCL assigned to it and the MCL is the maximum allowable amount any compound can be in the drinking water without it causing an increased probability to cause harm to human health.
The water supplier’s drinking water must be equal to or lower than the MCL in order to be in compliance. The measurement is in micrograms per liter (mg/l) or parts per billion (ppb). This is equivalent to finding one penny in a billion dimes. Bethpage Water District is not only compliant but is routinely non-detected for several dozen Northrop Grumman plume contaminants.
Bethpage Water District has also tested the water for safety as low as parts per trillion (ppt). This is ten times less than finding one person in all the people that have ever lived on Earth, alive or dead. Another scale analogy of 1 part per trillion is compared to looking for 1 blade of grass in a lawn that covers the entire town of Bethpage.