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Q & A: ice water in plastic bottles

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Most recent answer: 10/22/2007
Q:
Recently, I was told that it is bad to freeze water in plastic bottles and then drink them as they thaw out. We use these on the construction jobs and the ice holds the water cold all day.
- Dick (age 78)
Hayfork, CA
A:
Well, it certainly is not bad for you to drink icewater (unless you have some special sensitivity, such as sensitive teeth. I had a friend once who suffered asthma when he drank cold beverages).

What you may be asking about is whether the bottle may burst. Plastic water bottles these days are designed so that their contents may freeze without bursting the bottle (most of the time -- sometimes the plastic is a little weak and you get a leak). Bottles are not shaped spherically, but rather have indentations, lumps, bumps, and all kinds of odd shapes to them. The water expands as it freezes, and the bottle can deform as its volume needs to grow because the dents in the bottle can pop out.

Bottles also have these shapes because you'd like them not to burst when dropped. As one part of the bottle is crushed inwards on impact with the ground, another part of the bottle must bulge out because water isn't very compressible. Gallon jugs of milk have circular dents in their sides for just this purpose. You can tell if one's been dropped because its circular dents are popped outwards.

These features of plastic bottles don't always work, and you can still end up with water or milk all over the place, but it happens less often these days. Glass bottles are a real hazard.

Tom

(published on 10/22/2007)

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