Did you know that you can cool water below its freezing point at 32 °F (0 °C) without it becoming solid? This method of instant freezing is called “supercooling.” You can use salt, ice, and water to supercool water bottles in an instant.[1] Supercooled water will remain a liquid until something, like a tapping motion, instantly kickstarts the freezing process.

Part 1
Part 1 of 2:

Creating a Salt and Ice Water Mixture

  1. 1
    Pack your bucket or cooler about half full of ice. Your bucket or cooler should be large enough to hold both bottles of water without them touching each other. It should also be tall enough for the salt and ice water mixture to cover the water in your bottles.[2]
    • Check if your bucket is large enough by putting both water bottles in it while it’s still empty. You’ll be adding the water bottles after you create the salt and ice water mixture.
  2. 2
    Pour in enough water to allow the ice cubes to move. Slowly add tap water from a sink or faucet. You should add enough so that the ice cubes can move more easily, but they should not float to the surface of the water. You should have more ice than water in your bucket or cooler.[3]
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  3. 3
    Add 2 cups (600 g) of rock salt for every 10 lb (4.5 kg) of ice. Mix the rock salt into the ice water slowly using a large spoon or ladle. Mixing should be easy enough with the amount of water that you added to your ice.[4]
  4. 4
    Allow the temperature to reach 27 °F (−3 °C). Use your thermometer to check the temperature after about 30 minutes. It should be below the freezing point of water.
    • If it hasn’t dropped below that temperature, add 1 cup (300 g) of salt and mix.
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Part 2
Part 2 of 2:

Freezing Your Water Bottles

  1. 1
    Place the water bottles carefully in the ice water. Once your mixture is ready, add the water bottles. Make sure they don’t touch each other, which could make them freeze early. You can use all kinds of water: purified, distilled, spring, or deionized. Don’t use glass bottles, which can burst.[5]
    • Don't use tap water. Ice crystals can form around impurities in tap water, which will ruin the supercooling process.
  2. 2
    Allow the temperature to drop to 17 °F (−8 °C). Monitor your mixture with a thermometer over the next half hour to an hour until it reaches this temperature. Make sure the water in the bottles has not frozen.[6]
    • If the water has frozen, let the bottle thaw before trying again from the beginning.[7]
  3. 3
    Tap a water bottle firmly against a hard surface. You can hit the ground, kitchen counter, or table. Ice crystals will form at the top of the bottle and creep down to the bottom. Open the cap of your second water bottle, and it will freeze the same way without being tapped.[8]
    • The motion of unscrewing the cap on the second bottle is enough to set off the ice crystals.[9]
    • If the water doesn’t freeze, tap it more firmly. If that does not work, return it to the ice water mixture and let it cool for another 30 minutes before trying again.[10]
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Community Q&A

  • Question
    Why does it freeze so quickly?
    Landon Scott
    Landon Scott
    Community Answer
    It’s a chain reaction. Only one water particle has to be cold enough. So when you pound it, the particles collide and the energy releases to the rest of the water.
  • Question
    What type of rock salt do you use?
    Landon Scott
    Landon Scott
    Community Answer
    Sodium chloride and potassium chloride both work. Sodium chloride is just common table salt.
  • Question
    Can you use a freezer to make instant ice?
    Landon Scott
    Landon Scott
    Community Answer
    No, it requires the bottle to be surrounded by water and ice. You might possibly be able to get it to work just in a freezer, but it’s very unlikely to work.
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Warnings

  • Never use glass bottles when freezing bottled water. Glass can cool too quickly and cause the water to freeze in the ice bath. If the water freezes at this stage, the bottle can burst.
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Things You'll Need

  • Bucket or cooler
  • Ice
  • Tap water
  • 2 cups (600 g) of rock salt
  • 2 16.9 fluid ounces (0.50 L) unopened plastic bottles of purified or distilled water
  • Ladle or large spoon
  • Thermometer

About This Article

wikiHow Staff
Co-authored by:
wikiHow Staff Writer
This article was co-authored by wikiHow Staff. Our trained team of editors and researchers validate articles for accuracy and comprehensiveness. wikiHow's Content Management Team carefully monitors the work from our editorial staff to ensure that each article is backed by trusted research and meets our high quality standards. This article has been viewed 59,553 times.
48 votes - 66%
Co-authors: 9
Updated: September 16, 2022
Views: 59,553
Categories: Chemistry
Article SummaryX

To freeze water instantly, first, create a salt and ice water mixture by packing a bucket or cooler half full of ice and adding just enough water to allow the ice cubes to move. Next, toss in 2 cups of rock salt for every 10 pounds of ice and mix with a large spoon. Once you have your mixture, let it sit for about 30 minutes, or until it gets to about 27 degrees Fahrenheit. If it doesn’t drop below that temperature, mix in another cup of rock salt. As your mixture continues to cool, pour purified or distilled water in plastic water bottles and place the bottles in your bucket without them touching each other. Avoid using tap water, since the impurities will ruin the supercooling process. Keep monitoring the temperature until it reaches about 17 degrees Fahrenheit. When it does, grab a bottle and tap it against a hard surface, as this will cause ice crystals to form at the top of the bottle and creep down to the bottom. For more tips, including how to freeze the bottles without tapping them, read on.

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