Since the early 1970s, TOC has been an analytic technique used to measure water quality during the drinking water purification process. TOC in source waters comes from decaying natural organic matter (NOM) as well as synthetic sources. Humic acid, fulvic acid, amines, and urea are examples of NOM. Some detergents, pesticides, fertilizers, herbicides, industrial chemicals, and chlorinated organics are examples of synthetic sources. Before source water is treated for disinfection, TOC provides an estimate of the amount of NOM in the water source. In water treatment facilities, source water is subject to reaction with chlorine-containing disinfectants.  When the raw water is chlorinated, active chlorine compounds (Cl, HOCl, ClO) react with NOM to produce chlorinated disinfection byproducts (DBPs). Researchers have determined that higher levels of NOM in source water during the disinfection process will increase the amount of carcinogens in the processed drinking water.
With passage of the U.S. Safe Drinking Water Act in 2001, TOC analysis emerged as a quick and accurate alternative to the classical but more lengthy biological oxygen demand (BOD) and chemical oxygen demand (COD) tests traditionally reserved for assessing the pollution potential of wastewaters. Today, environmental agencies regulate the trace limits of DBPs in drinking water.  Recently published analytical methods, such as United States Environmental Protection Agency (EPA) method 415.3, support the Agencys Disinfectants and Disinfection Byproducts Rules,' which regulate the amount of NOM to prevent the formation of DBPs in finished waters.
The content of TOC is also an important parameter to evaluate the quality of organic shale resources which are one of the most important unconventional fuels. Numerous evaluation methods have been introduced, including these based on wireline logs and in situ techniques.