Expert: Dr. Henry Boyter, Jr. - 12/9/2006

Question
I live in Toronto.I got into my car this morning and I had two half full bottles of
water, one local spring water, the other "aquafina". The spring water was frozen
solid, the "osmotic demineralised" Aquafina, ready to drink. I understand why
they would do this, but what is in the "water" to stop it from freezing?

Answer
"Spring water" has minerals at low levels such as sodium chloride (salt), sodium carbonate, and other sodium salts.  Many "spring waters" are just Aquafina that they add salt back to and then raise the price by many times more than the cost of the salt added.  You can read more at

http://en.wikipedia.org/wiki/Spring_(hydrosphere)

Here is the problem, the Aquafina should have been frozen, not the mineral water.  Minerals cause the freezing point to be depressed (lowered), so in your case something else was going on.

Two possibilities that are related:

1. The amount of minerals was very low AND something else.  You said they were half full.  To me that means you had drunk out of the bottles and that means you literally have been "spitting" into them.  The materials from your mouth including things you might have been eating will be much greater in weight than any minerals in the "spring water".  The Aquafina had more "spit".

You were eating and drinking with the Aquafina, so you got crumbs and stuff in that bottle and the "minerals" are not significant.

2. Another possible answer is the bottles.  If the plastic on the aquafina is thicker, it may not have gotten as cold.


Try this.  Take one bottle of each and an empty bottle of each.  Pour half of the mineral water into the empty (and dry) Aquafina bottle and half the Aquafina into the empty mineral water bottle.  Be sure to mark them.  Put the lids on tight on all four and set them out at night.  I'd be interested to see what happened.