Aquafina Bottled Water Doesn't Freeze in Cold Temperatures-Truth!

Aquafina Bottled Water Doesn’t Freeze in Cold Temperatures-Truth!

Summary of eRumor:

Aquafina bottled water doesn’t freeze in cold temperatures, leading some to question what’s in it.

The Truth:

Aquafina bottled water doesn’t freeze when exposed to cold temperatures sometimes — but it’s not because of additives or chemicals. Aquafina bottled water doesn’t freeze sometimes because it’s too pure for ice crystals to form.
It’s not clear where rumors that Aquafina bottled water doesn’t freeze started, but they’ve been circulating since at least 2007. One of the earliest versions came from a message board post from a man who put a bottle of water in the freezer each night before bed. He’d sometimes awake in the morning to discover that Aquafina didn’t freeze overnight, or that it wouldn’t freeze until he unscrewed the cap.

Aquafina bottled water doesn’t freeze sometimes, but it’s not because of additives or chemicals.

The person who wrote the post understandably questioned what’s in Aquafina that prevents it from freezing. And the surprising answer? Nothing.  The University of Illinois Physics Department explains the phenomenon as “supercooled water.”  Water usually freezes at temperatures below zero degree celsius. But that’s only because impurities like dust are there start the ice crystallization process, called nucleation:

In the absence of impurities in the water and imperfections in the bottle, the water can get “stuck” in its liquid state as it cools off, even below its freezing point. We say this supercooled state is “metastable.” The water will stay liquid until something comes along to nucleate crystal growth. A speck of dust, or a flake of frost from the screw-cap falling into the bottle are enough to get the freezing going, and the crystals will build on each other and spread through the water in the bottle.

Of course, it’s possible for water freeze without a dust particle or something else to trigger nucleation. This type of ice formation, known as homogeneous nucleation, requires much colder external temperatures than zero degrees celsius, however. The true freezing point of water without impurities, the University of Manchester’s Center for Atmospheric Science reports, is -36 degrees celsius:

This is the true freezing temperature of pure water, but in everyday-land, pure water is rarely encountered, and water often contains some form of ice nuclei and thus freezes at around 0°C (in our ice-cube trays for example).  If it doesn’t freeze, it is said to be supercooled.

So, it’s true that Aquafina bottled water doesn’t freeze sometimes — but it’s only because there aren’t impurities in the water for ice crystals to form around, or because the temperature isn’t -36 degrees celsius — which is the true freezing point of water.
And, in case you’re wondering, Pepsi admits that Aquafina comes from municipal sources (like tap water). But the water is purified and filtered before it’s bottled.