Explanation of Terms
Maximum Contaminant Level (MCL)
The highest level of contaminant that is allowed in drinking water. MCLs are set as close to the MCLGs as feasible using the best available treatment technology.
Maximum Contaminant Level Goal (MCLG)
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.
Parts per million (ppm) or milligrams per liter (mg/L)
One part per million corresponds to one second in 11.5 days.
Parts per billion (ppb) or micrograms per liter (ug/L)
One part per billion corresponds to approximately 1 second in 31.7 years.
Action Level (AL)
The concentration of a contaminant which, if exceeded, triggers treatment or other requirements which a water system must follow.
Treatment Technique (TT)
A required process intended to reduce the level of a contaminant
Colony Forming Units (CFU)
A measurement used to count the number of bacteria colonies found in water
Nephelometric Turbidity Units (NTU)
A measure of suspended particles in water. High quality water has a low NTU.
Key to Tables
AL = Action Level
pci/L = picocuries per liter (measures radioactivity)
CFU = Colony Forming Units
ppm = parts per million, or milligrams per liter (mg/L)
ppb = parts per billion, or micrograms per liter (ug/L)
ppt = parts per trillion, or nanograms per liter
ppq = parts per quadrillion, or picograms per liter
MCL = Maximum Contaminant Level
MCLG = Maximum Contaminant Level Goal
MFL = Million fibers per liter
NTU = Nephelometric Turbidity Units
TT = treatment technique
ND = Not detected
n/a = not applicable