Water purification systems: a comparative analysis based on the occurrenceof disinfection by-products

Trihalomethanes (THMs) are halogenated hydrocarbons, and are by-products of the chlorination of drinking water. Most THMs are formed in drinking water when chlorine reacts with naturally occurring organic substances such as d ecomposing plant and animal materials. Risks for certain types of cancer ar e now being correlated with the presence of disinfection by-products (DBPs) . The present research uses gas chromatography to analyze the presence and levels of THMs in drinking water samples from a variety of sources. These i nclude (1) municipal drinking water from two south Florida counties (2) two brands of bottled water; (3) untreated residential well water; and (4) mun icipal tap water passed through additional water purification systems. The results are summarized in a tabular format, and the compliance of each wate r with existing US EPA-mandated standards is examined. General conclusions from this study are that all the waters tested complied with federal regula tions regarding THM levels, properly functioning home filtration units may be quite effective in further reducing DBP concentrations and, as expected, non-chlorinated waters such as bottled water and residential well water co ntain lower THM levels. (C) 1999 Elsevier Science Ltd. All rights reserved.