People are advised to stockpile bottled water in the event of an emergency, but do you know if your 20-pack of Dasani or Evian would stand the test of time? While some people might assume bottled water lasts for life---after all, it's water---studies have shown that certain conditions might decrease the chance of bottled water being safe or tasty to drink.
The Official Word
Both the International Bottle Water Association and the U.S. Food and Drug Administration (FDA) consider bottled water to have an indefinite shelf life, so long as it is produced in accordance with current good manufacturing practices and properly stored. However, the FDA concedes that storing water bottles for long periods of time can result in a slightly different odor or taste.
The FDA defines a proper storage environment as being unopened, in a cool place (room temperature or lower), out of direct sunlight and away from chemicals (such as cleaning agents, paints, solvents or gasoline). It is recommended that bottled water not be stored for long periods of time in a garage. When bottled water has been opened, most agencies agree that it has at most a two-week shelf life if kept refrigerated; otherwise, it will begin to develop bacteria and algae.
While the FDA does not require expiration dates to be printed on bottled water, some manufacturers voluntary mark their containers with a two-year expiration date. Most agree that this practice originated with a 1987 law required by the state of New Jersey to put an expiration date on all food products (including water); however, in 2004, New Jersey changed the law to simply mark the bottle with the date produced.
In recent years, a host of studies have found high levels of toxicity in a variety of different plastics, especially recycle numbers 3, 6 and 7. While bottled water is usually manufactured as recycle number 1, which is generally considered less toxic, leeching can occur especially as plastic ages. A 2008 study conducted by the Environmental Working Group found more than 38 chemical pollutants in the 10 most popular bottled water brands, raising questions about both the water's origins and the plastic it's housed in over time.
Although water bottles do not technically expire, especially if kept at ideal conditions, many environmental groups recommend consuming water bottles within a two-year period. Or better yet, not consuming bottled water unless you have to---the environmental impact of producing the bottles and the potential chemical side effects might exceed the convenience factor that water bottles typically provide.