I usually have a bottle of water in my car. During the summer, it heats up quite a bit in the sun, so I toss it. I could just wait until it cools back down, but am afraid of potential bacteria buildup. Is this a legitimate concern?
In the winter, it freezes. But in that case, I just wait until it melts and continue to drink from it. Is there any danger in doing this?
Depends on the type of bottle it is: Plastic Bottles on Snopes.
You aren’t really supposed to heat up plastic of any sort, so it depends on how hot the car gets. Personally, I wouldn’t drink the water from a bottle that’s been heated in the car. On the occassions I have, I noticed a distinct plastic taste, which probably isn’t a good thing.
Doesn’t this depend on your costs? If your car breaks down in the desert, and your survival is at stake, I seriously advise you not to throw out the water. If, on the other hand, all you’re doing is tossing the water onto the azaleas and refilling the bottle from the tap – why not? Do you need any more reason than that the nice cool fresh water tastes better?
I would be surprised if anything really got going in your hot water. Generally the bacteria that can grow inside us, e.g. E. coli, like body temperature, and don’t do especially well at higher or lower temperatures. They may or may not die – they have remarkable survival abilities – but they won’t grow very fast.
Also, I don’t think the freezing is especially helpful. It certainly stops the growth of bacteria, but many can survive freezing and thawing just fine. Generally high heat, e.g. about 130 F or so, is more bacteriacidal.