First, a shocker: water itself doesn’t really expire. It’s just H2O. But your bottle? That’s a whole different story. Once you crack the seal, you invite the real party crashers: bacteria, dust, and your own backwash. The FDA doesn’t set a hard rule for “expiration” after opening. They leave it to manufacturers, who usually slap on a date for quality, not safety.
Think of it like this: your water won’t turn into poison. But it might start tasting like your gym socks. That’s because plastic bottles can leach chemicals over time, especially if they get warm. And micro-organisms from your mouth? They love a warm, dark bottle. It’s basically a tiny, gross hot tub.
