18Common Water Chemistry/Quality Definitions
Units of Measurement
mg/l = Milligrams per liter. One milligram per liter equals one packet of artificial sweetener
sprinkled into 250 gallons of iced tea.
μg/l = Micrograms per liter. One microgram per liter is equal to one packet of artificial sweetener
sprinkled into an Olympic-size swimming pool.
NTU = Nephelometric Turbidity Units. A measurement on the cloudiness of the water.
pCi/I = Picocuries per liter. A measure of radioactivity.
Acronyms
Maximum Contaminant Level (MCL) - The highest level of a contaminant that is allowed in
drinking water.
Maximum Contaminant Level Goal (MCLG) - The level of a contaminant in drinking water
below which there is no known or expected risk to health.
Treatment Technique (TT) - A required process intended to reduce the level of a contaminant
in drinking water.
Action Level (AL) - The concentration of a contaminant that, if exceeded, triggers treatment or
other requirements which a water system must follow.