A Theriac in Digestif Form
Making Huge Clear Cubes to Prep for Ice Diamonds and Spheres

Is Pure TDS 0 Water Actually Bad for Making Clear Ice?

Here's an interesting problem and solution: James Hogarth reached out to me to describe the following. He is using water filtered with a Zero Water filter in a clear ice system. This filter removes all the major dissolved solids in the water, and it comes with a little TDS meter to verify it. But the supposed-to-be-clear ice that comes out from this water has streaks remaining, but regular tap water doesn't. 

My tap water has a terrible taste, however, when I freeze tap water [in the Wintersmith’s Phantom] it does freeze perfectly clear. The bad news is that if I then thaw the water it still retains a bad taste. It is improved but still not good.

Curiously, the ZeroWater filter comes with a Total Dissolved Solids meter, and while not the most sophisticated meter in the world, it reads around 110-120 on tap water and perfect 0 for the thawed water. 

So right now I either get great tasting ice with air bubble streaks, or perfectly clear ice that tastes terrible.

Even distilled water gave me streaks of air bubbles. My freezer was always right around 0 degrees, and multiple different molds, no mater what, boiled or not, still got streaks.


He theorized that his water was actually freezing too fast without salt and other minerals in it that would naturally slow the rate of freezing. 

So to test the theory, he tried adding table salt to TDS 0 water - and it was successful! He added a concentrated salt solution to the rest of the water to try to bring it around 135 ppm before freezing. 

I know that ice crystals will push out salt molecules as the ice crystalline structure does not have room for it. Freezing water is one method for desalination of sea water for this reason, it just isn’t very energy efficient.

The melted ice tastes just as good as the filtered water. From the top half [the clear part], the meter reads 6 and the bottom half 163.

So after a few more batches of ice, and a few bottles of whiskey, it seems that around 140-180 ppm of table salt in the ZeroWater is ideal. I get crystal clear ice, and when I melt the ice and test it, it’s usually 6ppm salt or less.


We knew that freezing water pushes the trapped air and impurities (including the minerals) to the last part of ice to freeze. What's interesting here is that at least in this case, the presence of "impurities" while freezing seems to improve the clarity of the ice, and we can theorize that is because they slow the rate of freezing. 


Hogarth later tried other minerals, including mineral drops that are sold to supposedly make water healthier. He found they acted in much the same way, concentrating in the cloudy part of the ice. 

Trace Mineral Drops: starting at 204 ppm, melts to 23 ppm. So something is clearly less filtered from directional freezing than salt or calcium chloride. Both of which could be as high as 240-250 ppm and the melted ice would be around 6ppm. I don’t have the tools to tell you what it is though.


So I'll leave this at that. To replicate it, I (or better yet, you) could try freezing two identical quantities of water in identically-shaped insulated trays: one with TDS 0 and one with some dissolved solids.

This might not be an issue if your freezer temperature is higher and closer to the freezing point, but most freezers have maximum temperatures much lower than that for food safety. 


Ice with Streaks



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Good post. I have encountered these streaks in my ice but I would not have considered that my water was *too* pure. Something more to try! Thanks, Camper.

Mr. E

Confirmed. I use carbon filtered water built-in to my Whirlpool fridge, and have very clear results. My girlfriend uses TDS near zero from a nearby vendor of distilled water, and gets the bubble streaks in her LG (we share the same Coleman cooler). Btw, is distilled water truly boiled, or just thoroughly de-ionized? that's a massive amount of fossil fuel energy to make that much steam for those who could get the same or better TDS from de-ionized. Lastly, in my Coleman cooler, I usually get a small gurgling volcano in one corner of the block and then I shave off the cloudy frozen lava later- I cover the cooler with a cutting board, but it still happens. Any ideas?

Camper English

@Mr. E Thanks. Yes distilled water is boiled and then the steam condensed; at least by definition of "distilled." Not sure if you could sell it as such if it was just filtered but on the other hand it could be like "nut milk" so I guess I'm not sure!

Volcano - I think I know what you mean and I do not know what's up with it - I used to get them in my old freezer, but only some of the time. My theory is that it's still something to do with the fan- on the other hand is it possible that it Only occurs when you cover it with the cutting board? Thinking back on it that might be the case for me. Perhaps it's condensation that drips/slides off that side to create it during the initial freezing period? Just a guess.

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