This research covers the determination of the existing situation of trihalo
methane (THM) levels in the distribution system of Ankara City and also foc
uses on the investigation of effectiveness of granular activated carbon (GA
C) adsorption for the removal of natural organic matter (NOM) that are THM
precursors and also THMs. For this purpose, a survey was carried out at 14
selected points in the city and the THMs were observed to be present in the
Ivedik Water Treatment Plant (IWTP) filter effluent and in the distributio
n system (DS). THM concentrations increased within the DS, however, total T
HM (TTHM) levels did not exceed the EPA Stage I Limit of 80 mug/L.