Alphabet Soup:
Whattheheck's an MCL?
Acronyms and Abbreviations (like DW, mg/L, and EPA) are everywhere in the water business. Here's a handy but hardly comprehensive list of some common ones.
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mg/L: A MilliGram per Liter is roughly one part per million. A concentration of 1 mg/L could be represented approximately by adding four drops of food coloring to a fifty-five-gallon drum. It is equivalent to one minute in two years. Note: a µg/L is a microgram per liter, the equivalent of a part per billion. Think of a drop of food coloring in a large motel swimming pool.
PPB: A Part Per Billion means of one of a billion things. For example, if the population of the United States were 500 million (half a billion), then 2 ppb would be the equivalent of one person from the entire population. A ppb is equivalent to one second in 32 years. Sometimes ppb is rendered as µg/L, meaning micrograms per liter.
TTHM: Disinfectant byproducts governed by EPA regulations include "Total TriHaloMethanes." The most commonly known trihalomethane is choloroform. The DBP regulations lump together four DBPs and their total concentration must be below the Maximum Contaminant Level of 80 ppb. Denver Water averaged 33 ppb in 2004 and 32 in 2005.
HAA5: Disinfectant byproducts governed by EPA regulations include a group of five HaloAcetic Acids. The Maximum Contaminant Level is 60 ppb, and Denver Water averaged 20 in both 2005 and 2004.
LT2: Shorthand for "Long-Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR)," a regulation added by the EPA in 2005 which covers treatment and detection of microorganisms such as Cryptosporidium in drinking water.
DBP2: Shorthand for "Stage 2 Disinfectants and Disinfection Byproducts Rule (Stage 2 DBPR)," a regulation added by the EPA in 2005 which, in conjunction with the Stage 1 rule, covers the use of disinfectants to control microorganisms, the removal of organic substances that contribute to byproduct formation, and allowable concentrations of disinfectant byproducts.
MCL: The "Maximum Contaminant Level" allowed when detecting substances in drinking water. MCLs are measured in various ways. Often the value is in parts per billion (ppb), but other measures are used sometimes. For example, current regulations allow a maximum of 80 ppb of TTHMs in the water, but 2 parts per million of barium. Two parts per million would be the same as 2,000 parts per billion.
TOC: The Total Organic Concentration measures the amount of organic material in the water.