Can You Really Make Crystal-Clear Ice Cubes With Boiling Water?

Can You Really Make Crystal-Clear Ice Cubes With Boiling Water?

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Kelli Foster
Apr 29, 2015
(Image credit: Kelli Foster)

Whether you have a built-in ice maker in the freezer or you make ice cubes the old fashioned way, you've probably noticed that your ice cubes appear cloudy and opaque. But, go to a restaurant or fancy cocktail bar and you're likely to find crystal-clear cubes sitting on the bottom of the glass. Ever wonder how that happens?

Well, there could be an easy way to get super crystal-clear ice at home.

The ice that comes out of your freezer is usually milky-colored, not clear. Why? The reason most homemade ice looks this way is because of air trapped in the water.

The Original Tip

There are a few variations on this tip, but the simple premise is that first boiling the water you'll use to make the ice will remove dissolved air from the water, ultimately yielding clear ice cubes. Some tips recommend sticking with filtered water for the best results, while others suggest this will also work with tap water. Some tips also suggest boiling the water twice.

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(Image credit: Kelli Foster)

The Testing Method

I did this experiment twice: the first time using tap water and the second time using filtered water. I also followed the same process each time.

I used a kettle to bring water to a boil, let it cool most of the way, then brought the water to a boil again. I filled one side of an ice cube tray with boiling water, and the other side with room temperature water. Then, I placed the ice cube tray in the freezer overnight. In the morning, when the ice was frozen through, I removed the cubes from the tray.

Ice made with boiling tap water (left) and made with room temperature tap water (right).
(Image credit: Kelli Foster)
Ice made with boiling filtered water (left) and made with room temperature filtered water (right).
(Image credit: Kelli Foster)

The Results

While I wasn't able to achieve crystal-clear ice, there was a distinct and very noticeable difference between the ice cubes made with boiling water and those made with room temperature water. The cubes made with boiling water were mostly transparent — they were clear on top and at least halfway down the cube, with a small cloudy patch on the bottom. All of the ice made with room temperature water had a larger cloudy patch on the bottom of the cubes.

There was also a noticeable difference between the ice cubes made with filtered water and those made with tap water. Filtered water made for clearer ice cubes with smaller cloudy patches, both ones that were made with boiling water and the ones that were made with room temperature water.

Verdict: This is not a mind-blowing tip!

Final Notes

The key to pure, crystal-clear ice is pure water. It could be that there were still traces of minerals and/or air in the water I used.

I don't see myself using this method on a regular basis. I have an ice maker in my freezer, and I'm happy to rely on that. Though, if I was a hosting a small cocktail party or gathering on a special occasion I'd probably go the extra step to make mostly clear ice.

Have you ever tried this method to make clear ice cubes at home?

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