Determination of trihalomethanes in tap water of different origin in Republic of Macedonia

Trihalomethanes (THMs) are formed in water the chlorine used in water-treatment plants react with organic matter. THMs are suspected carcinogens. The goal of this study is determination of the concentration of THMS in potable water after chlorination. The study included 60 samples of potable water from water facilities that draw water from accumulations and 70 samples of potable water from water facilities that draw water from boreholes and springs. Samples were analysed by GC-ECD method with headspace technique. The obtained results for individual THMs in samples of potable water that draw water from accumulations, range from 15 – 55 µg/l for chloroform; 12 – 27 µg/l for dichlorobromomethane; 2-6 µg/l for chlorodibromomethane and 3 – 13 µg/l for bromoform. The obtained results for individual THMs in samples of potable water that draw water from boreholes and springs range from 5 – 15 µg/l for chloroform; 1 - 5 µg/l for dichlorobromomethane; 1- 3 µg/l for chlorodibromomethane and 1-5 µg/l for bromoform. According to the national Regulation for Water Safety (46/08), the content of chloroform in 7 of tested samples of potable water that draw water from accumulations exceeded the MRL value (30 µg/l). The concentration of THMs in potable water after chlorination that comes from water facilities as wells and springs show significant decreasing trend in comparison with concentration of THMs in potable water that comes from accumulations (p