Have you ever kept a glass of unsealed water by the bed throughout the night? Did it not taste ‘off’ when you drank it the next morning? You may think that the glass of water has lost all its freshness. But is it possible for water to expire?
If you see it has bubbles, you might want to think twice before you drink it.
When it comes to water that seems stale, several factors may be involved. Firstly, it’s important to note that water isn’t only made up of H20 molecules – it also contains plenty of other molecules and ions that can alter the taste of plain, old water.
Whether it’s from the tap or from the bottle, water that’s been sitting overnight will start undergoing some chemical reactions. That’s because water absorbs the carbon dioxide from the environment. This alters its natural pH and makes it more acidic (which explains the off-taste). But if it’s been sitting out in a clean glass for just one night, it should be safe to drink.
Just be warned: this may still expose it to possible contamination (especially if you re-using a dirty glass). A lower pH also makes it easier for bacteria to grow, so you should always take precautions.
Water is an element prone to life. It can grow algae and bacteria when kept unsealed for long. As with most of your stuff, really, the longer that a glass of water is left hanging out somewhere, the more harmful bacteria it can be exposed to.
Be mindful especially of tap water that’s been stored for an extended period of time, and of the plastic water bottles that have been sitting in your hot car. Consuming either can expose you to germs or harmful chemicals like BPA.