Since we've had a slew of water threads today, I thought I'd continue.

What would be the shelf life be of water no longer in a factory sealed container? For instance, if you took a Nalgene or even a Poland Springs bottle, filled it with tap water or store bought water (or mostly filled it, if expansion from freezing was a concern), and put it in your preps, either in a house or a vehicle? How long could you expect the water to stay "good" under normal or even widely varying climates?