Polyethylene terephthalate (PET) is a widely used material for the packaging of drinking water. The development of this research arises from the demand of a popular Turkish drinking water company, which has reported odour problems in their PET bottled products. Acetaldehyde, cobalt, and antimony contents were determined in bottled water of different volumes (0.5, 1.5, and 5 L), PET bottles, plastic blue closures, and preform material by gas chromatography mass spectrometry (GC-MS) and inductively coupled plasma mass spectrometry (ICP-MS). Antimony, cobalt, and acetaldehyde migration into the drinking water (PET bottled) was tracked for every 2 months through a year. Migration of these compounds rose with increased storage time at 20 degrees C. The highest amounts of migrated compounds were observed in 0.5 L (smallest) of PET bottles. All migration results were found to be under the migration limit at the end of storage period. In addition to these findings, nonintentionally added substances (NIASs) analyses were performed by headspace (HS)/GC-MS. Odour-active compounds were identified using the library database. Off-odours in the drinking water were due to the migration of various compounds such as acetaldehyde and other NIASs from PET bottle into the drinking water. In addition, acetaldehyde amounts were ranged from 0 to 140 mu g/L in all drinking waters, and some acetaldehyde values were above the taste threshold of 15 mu g/L.