A method based on isotope dilution headspace solid-phase microextraction and gas chromatography/mass spectrometry was used to assess levels of bisphenol A (BPA) in 56 samples of bottled water products sold in Canada. Levels of BPA in samples of all 51 non-polycarbonate (PC) bottled water products were lower than the method detection limit (0.50 µg l(-1)). Levels of BPA in most bottled water products in PC carboys were low, ranging from <0.50 to 1.4 µg l(-1) with an average of 0.75 µg l(-1). However, BPA was detected at levels of 8.8 and 6.5 µg l(-1) in two bottles of the bottled water products in PC carboys from the same product analysed over a 5-week period, likely due to accidental or careless exposure of the products to heat (e.g. under the sun) during storage and/or transportation for extended periods of time.