The water treatment procedure can lead to the formation of by-products, when the drinking water source is contaminated with trace amounts of organic matter. In this study, the disinfection by-products (DBPs) of trace organic compounds were identified to provide the knowledge on the possible DBPs of the contaminated water during the general or emergent water treatment procedure. Chlorination or ozonation was performed in the laboratory scale under the conditions for the drinking water treatments, and the DBPs of 16 VOCs and 4 phenols were screened using gas chromatography/mass spectrometry (GC/MS). By the chlorination, dichlorobenzene was produced from benzene, ethylbenzene and styrene. 1,2-dichloroethane, 1,2-dichloropropane and phenol produced 1,1,1-trichloroethane, chloroform and chlorophenol, respectively. By the ozonation, bromoform changed to dibromomethane and styrene produced benzaldehyde. Finally, the water treatment method of each classified contaminant group was suggested for the emergency control of contamination.