A comprehensive investigation into the occurrence of odor problem at 111 drinking water treatment plants (DWTPs) in major cities across China was undertaken using both flavor profile analysis (FPA) and gas chromatography–mass spectrometry (GC-MS). Eighty percent of source water samples exhibited odor problems, characterized by earthy/musty (41%) and swampy/septic (36%) odors, while the occurrence rate was lower (45%) in the finished water. Source water from rivers exhibited more pollution-origin odors, such as the swampy/septic odor, while that from lakes and reservoirs exhibited more algae-origin odors, such as earthy/musty odors. The occurrence rate of 2-methylisoborneol (2-MIB) in the surface source water samples was 75%, with 7% of samples containing 2-MIB concentrations of over 10 ng·L^-1. The earthy/musty odor in the lake/reservoir water samples was mainly caused by 2-MIB (linear regression coefficient, R²=0.69), while the correlation between 2-MIB concentration and the earthy/musty odor intensity in the river-source water samples was weak (R²=0.35). These results will be useful for the management of odor-quality problems in drinking water of China.