SEASONAL-VARIATIONS OF THMS IN SAUDI-ARABIAN DRINKING-WATER

Samples collected from the distribution systems of eight major cities in Saudi Arabia showed that trihalomethanes (THMs) occurred in all the water supplies. Concentrations ranged between 0.03 and 41.7 mu/L, much lower than the 250-mug/L limit set by the Saudi Arabian Standards Organization. Median total THM concentrations in the cities of Riyadh, Jeddah, Madinah, Makkah, and Abha were higher during the summer than in the winter. In addition, THM concentrations were low in cities that did not mix groundwater and desalinated water. Brominated THMs dominated (with bromoform the most abundant) and existed at the highest concentration levels, whereas chloroform was the least prevalent compound. This is the opposite of the occurrence pattern found in almost all water distribution systems worldwide.