This study focuses on the occurrence of two selected biocides, namely triclosan (TCS) and chlorhexidine (CHX), in the drinking water system of Ankara, Turkey. Samples were taken from the three main components of the drinking water system (camlidere and Kesikkopru Reservoirs, Ivedik Water Treatment Plant (IWTP) and the distribution network). Seasonal variations in biocide levels as well as their relation to general water quality parameters were sought. TCS levels detected in camlidere and Kesikkopru Reservoirs were in the range of 0.65-11.15 ng/L and 0.86-48.96 ng/L, respectively; whereas CHX levels detected were between <1.33-5.31 ng/L. TCS was completely removed in IWTP. In accordance with the result for the IWTP outlet, biocides in the distribution network were all below the limit of quantifications. Moreover, some conventional water quality parameters were related to the concentrations of biocides in surface waters.