No, most commercially bottled water companies do not put expiration dates on their products. This is because the FDA does not require them to do so. However, if you take a look at the bottle, you'll probably see a "best before" date. This date is determined by the company and it indicates how long the water will retain its optimum flavor and quality. The reason behind this expiration date is due to the plastic packaging. Over time, the plastic can start to leach chemicals into the water, which can give it an off-taste. Moreover, the bottle itself can start to degrade and break down over time, which can also affect the quality of the water.