Imagine you bought a bag of potato chips and left it open for a month. You wouldn’t eat those stale, soggy chips, right? Well, water doesn’t get stale exactly, but it does attract bacteria if the seal is broken. Once you open a bottle, you’ve invited the whole neighborhood—dust, germs from your mouth, and tiny airborne particles—inside.
If you’ve ever taken a sip from a bottle that’s been sitting on your nightstand for three days, you know that taste. It’s not “bad,” just… flat. It’s the taste of your own backwash mingling with the air. That’s why tap water left in a glass overnight starts to taste off—carbon dioxide dissolves into it, making it slightly acidic.
