Why does bottled water have an expiration date?

All companies that produce consumables must, by federal law, have an expiration date on it. Since bottled water is a consumable the company must put a expiration date on it.
Also some water becomes impure due to plastic melting or substances released into the water by the plastic.

Expiration Dates on Bottled Water

Here are opinions and answers from WikiAnswerers:

  • So that if you don't drink the water by that date you have to go out and buy a new bottle, thus creating more profit for the company which sold you the water
  • There is a chance that over time (years), the container could cause the water to have a different taste. There is much more information at the website in the Links section.
  • There are two main types of sterilization that all food and drink manufacturers use. The first is the use of peracetic acid that gives an instant kill to most pathogens (bugs that make you ill). The second is the use of steam. Holding a steam temperature of above 120 degrees in the product line for 15 minutes will kill virtually all pathogens. However, some bacteria form spores which are virtually indestructible and can last for millions of years. The only way to make totally sterile drinks would be to irradiate them, which wouldn't make them radioactive, but would make them cost a great deal of money to produce. Thus, the manufacturer cannot guarantee that their product is free of pathogens and gives it a 'use by' to minimize their liability. Packaging deterioration is the other reason for the "Best By" Date.

Please do not make the mistake of thinking that "Bottled Water" means pure, sterile, perfect water. It may surprise you to know that there is very little regulation concerning 'bottled water'. For example, it is common practice to label the bottle with such things as " Spring Water" or "Mountain fresh" while the water is actually taken directly from municipal sources! Look for yourself at the fine print and see.

Additional Information:

The information above is accurate and well written. Irradiation is, however, not all that expensive, as all that is required is to expose the water to a radioactive source. It is very passive. The problem is that consumers are less than excited about drinking "irradiated" water. The second problem is planned obsolescence. Water with a shelf life must be replaced whether it is consumed or not, which increases sales.

Bottled water is, for the most part, an ecological disaster. The plastic is not fully recycled--much of it ends up in land fills, or burned in waste to energy plants. Also, municipal water supplies are just as safe, and frequently safer, than bottled water--which often comes from municipal water supplies--as noted above.

Here are additions to the answer:

It is just giving warning that it will taste different from what it did when bottled.

They're is an expiration on water bottles because most of the time companies will put fluoride in water and the fluoride expires so they need an expiration date

Bottled water is pointless, If you had to choose between water that had chemicals put into it or natural pure water, the natural water is better because it has fluorine in it and most of the bottled water won't have fluorine. Plus, how can water expire within a protected container? Because plastic would take a long time to decompose and water wouldn't expire in it.

Water kept in a plastic container is harmful because bottles are made up of toxic substances which are harmful for both animal and plant life.In nature, as per its property water flows which keeps it clean and pure, not allowing any source of crude deposition. But water if kept enclosed for a prolong period allows anaerobic algae and other microbes to grow in it;making it unsafe and unfit for potable use. Hence, pouched water possesses an expiration date on it. The plastic chemicals will get to it. The water can go stale, too.