Speciation and distribution of trihalomethanes in the drinking water of Hong Kong

Chlorine is commonly used as a disinfectant in the drinking water treatment process. However, chlorine may react with organic precursors such as humic substances in water to form trihalomethanes (THMs). Since THMs are known c arcinogens, their concentrations in water should be monitored. The aim of t his research was to measure the concentrations of THMs in drinking water in the 19 districts of Hong Kong. This study also reports, for the first time , trihalomethanes-formation potential (THM-FP) of the drinking water in Hon g Kong. While the THM-FP values measured are all below the WHO guideline va lues, the total concentrations of THMs in tap water samples from 4 out of t he 19 districts exceed the U.S. and U.K, standards. The measurements show t otal THM levels of 104 mu g/L, 106 mu g/L, 115 mu g/L, and 131 mu g/L in Yu en Long, Tsuen Wan, North, and Tai Po, respectively. Such high levels of or ganic precursors could be an indication of the deteriorating state of the D ongjiang River in Guangdong, where over 70% of Hong Kong's drinking water o riginates. (C) 1999 Elsevier Science Ltd.