A purge and trap, gas chromatography system was developed to analyze for trihalomethane (THMs) compounds at the ppb (parts per billion) level in drinking water. Monthly influent and effluent samples were taken from three Weber Basin Water Conservancy Distrcit treatment plants, three Salt Lake City water treatmetn platns, and one Slat Lake Metropolitan water treatment plant. In addition tap water samples were taken at various business and residential locations in Salt Lake City, Utah, and Ogen, Utah. All samples were analyzed for trihalomethanes and total organic carbon (TOC). In addition to monthly sampling, a comparison of the production of THMs during post and prechlorination of water at the Parleys Water Treatment Plant in Salt Lake City was conducted. moving th epoint of chlorination within the treatment plant did not appear to reudce trihalomethane levels in the finished product. Highest trihalomethane levels (84 ug/1) occurred in the summer months with the lowest levels (<1 ug/1) recorded in the winter. The chemical form of the THMs varied from chloroform to the more brominated hydrocarbon from late winter through spring.
Peters, Thomas; Adams, V. Dean; and George, Dennis B., "The Occurrence of Trihalomethane Compounds in Salt Lake City and Ogden, Utah, Drinking Water Supplies" (1981). Reports. Paper 163.