This is a plastic water bottle.
Estimated persistence
≈ 500 years
Why it matters
Most single-use bottles are PET plastic (#1). They are cheap, light, and durable, which is why they are everywhere. That same durability is the problem. In the environment, PET does not disappear so much as fragment slowly into smaller and smaller pieces.
A bottle like this is often used once, maybe for a day, and then discarded. Even when it is recycled, a large share is not, and recycling itself is a downcycling pipeline with losses at every step. The result is a short use window followed by a very long materials problem.
Details
Mechanism
PET is used because it is cheap, clear, light, and strong. Those same properties make it useful for packaging and stubborn as waste.
After disposal
After disposal, bottles are landfilled, littered, or only partially recovered. Outside managed systems they weather, crack, and fragment instead of cleanly biodegrading.
Better substitutes
A reusable bottle with tap water or refill stations removes the repeat purchase. Treat bottled water as an exception rather than a background habit. When bottled water is unavoidable, buying less often and recycling correctly, with local cap and sorting rules in mind, is the practical fallback.