The effect of two environmental variables, ultraviolet radiation and external air temperature, on polyethylene terephthalate (PET) bottled water was investigated over 100 days. The high pressure liquid chromatography results showed the migration of carbonyl compounds (acetaldehyde, formaldehyde and acetone) from PET bottles into water over 3 months. Storage of PET bottled water enhanced the process of carbonyl compounds migration especially under sunlight. The combination of these two environmental variables caused an increase of 15% in each carbonyl compound compared with storage in the dark at the laboratory. The maximum ambient Ultraviolet-B, Ultraviolet-A and Photo-synthetically Active Radiation intensity at the solar noon were 1.95, 23.0 W/m2 and 100,000 Lux, respectively.