Using the standard total culturable virus assay-most probable number (TCVA-MPN) method, we evaluated a total of 348 samples, including surface water, finished water, and tap water samples, collected from randomly selected water treatment plants in Korea from August 2001 through July 2005 according to the Information Collection Rule. All the TCVA-positive samples were also subjected to integrated cell culture-PCR (ICC-PCR) methods for the detection of enteroviruses, hepatitis A virus, adenoviruses, and reoviruses. The most probable number of infectious units per 100 liters for the environmental water samples ranged from 0.5 to 47.3. Nine of the 13 TCVA-positive samples (69.2%) were found by ICC-PCR to be positive for human enteroviruses, which were confirmed to be coxsackievirus type B3, coxsackievirus type B4, coxsackievirus type B6, echovirus type 30, and vaccine strain poliovirus type 3 by direct sequencing. Eleven of the 13 TCVA-positive samples (84.6%) were found by ICC-PCR assay to be positive for reoviruses. The serotype of all the reoviruses was the same as reovirus type 1 by direct sequencing. Both enteroviruses and reoviruses were concurrently detected in seven TCVA-positive samples (53.8%).