Distilled water for mixing engine coolant?

I'm curious what the "ideal" water would be for coolant mixing. PH, TDS, GH?
Is RO water with a TDS of 50 as good a de-ionized? Does it really matter?
 
I use demineralized water from the hardware store. It's only a couple of dollars a gallon. I mix it 50/50 with Nulon One coolant that's rated for 10 years or 600,000 miles of service life. So far I've had zero cooling system related problems with any of my vehicles.
 
I have never seen an automotive repair facility with an inventory of distilled or deionized water jugs sitting on the shelf.
You are of coruse correct and itis nonetheless creepy.
I always bring the disilled water with the car if I ever need a need rad or hoses done so there is no incentive for folks to just run tap water.
 
I've always used distilled but have also read from authoritative sources that deionized is acceptable too. I've never questioned it until seeing this thread. Rislone seems to suggest softened water is preferable to distilled for similar reasons you stated:

https://rislone.com/blog/cooling/why-you-should-never-use-distilled-water-in-your-cooling-system/
No offense to the person who linked it, but this is an odd article, and the "reasoning" is spurious.
Its late and I dont want to type too much but I recommend to follow the rest of this thread over that link.
 
No offense to the person who linked it, but this is an odd article, and the "reasoning" is spurious.
Its late and I dont want to type too much but I recommend to follow the rest of this thread over that link.

Oh no, don't get me wrong as I don't believe any of that. Only distilled or deionized for me!
 
To recap; distilled may or may not be The Best Possible Option, but it is a reasonable option that is easily found.
 
A little intro first. If you were to search my user name you'll find it scattered all over the net , mostly in technical forums. I've a fair amount of technical experience in a lot of different areas. I've very occasionally mined this forum for intel for years, but never really had reason to participate until now. I've a question that this forum seems best poised to address.
I first ran a search and didn't really find what I was looking for. The universal advice with diluting coolant is to use distilled water. No need to go into why to not use tap water. I have first hand experience with that from before I knew better. If I've missed a thread that really addresses my question then please point me to it.

However, distilled water is fairly active chemically. Those ions that were stripped out of it in the distillation process have left behind "holes" that want to be filled. Ooo lookie, some heated aluminum! That sort of thing......

In steam turbine generators the chemistry of the water used is very carefully monitored and controlled. They start with RO water, then distill it. And then add back in very specific chemicals in very specific amounts to arrive at precisely the right water chemistry. Whatever that is. Learning this while I worked at one of those steam turbine generating plants started me in questioning the near universal distilled water doctrine.

So, is distilled really the best answer? If not, assuming it exists what is the better answer?
This is somewhat of a typical complaint that in actual practice makes zero difference whatsoever.

RO, distilled and deionized water are essentially the same thing. Undesirable ions are removed and are not exchanged for another. Water softeners are ion-exchange resins and exchange certain metallic ions for sodium (or in some cases potassium). Note it is a sodium ion, not sodium chloride or salt. Soft water does not contain salt from the resin.

But here's the thing. Yes deionized water will dissolve metals, but so will any other water that has a low concentration of the metal. Tap water probably has a low concentration of aluminum, so it will dissolve just as much as DI water.

However, in a closed system such as an automotive cooling system the water will quickly reach saturation. So the actual amount of metal being removed is in the micrograms. The only time DI water corrosion is an issue is one where the system is open, such as a distillation plant that is continually producing the water and it is flowing out of the system.

Plus the fact that coolants have passivation chemicals in them to help prevent corrosion. This is never a problem.

DI, distilled or RO water is always the best choice for mixing with coolant. You do not want to pre-load the chelating agents in the coolant with hard water. Some domestic water is naturally very low in minerals and can be used (such as the water here in the City of Milwaukee). But not all water is low in minerals, so using a demineralized water is always a good choice.
 
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Have a couple of old tractors that used well water only...or whatever water was available, I'm sure some of the water used was roof runoff, no antifreeze and the owners manual had you drain them in the winter. Most boats are like that still. One of those tractors is a 1949 model on it's original engine. I keep some green in it now but the rest is just tap water.
A dissolved solids meter does tell me that distilled water has less DS than my tap was or bottled water, but my city water has a DS count of 25, distilled is 7PPM and the health guidance says 500PPM is safe to drink. Of course, one can't tell what the dissolved solids are.
 
I'm curious what the "ideal" water would be for coolant mixing. PH, TDS, GH?
Is RO water with a TDS of 50 as good a de-ionized? Does it really matter?
No, Deionized should be 0ppm.
Does it really matter? No and yes. Would you see a difference in a well maintained vehicle following recommended service interval...probably no.
Would that coolant degrade more quickly, technically yes.

The ideal is 7pH, 0 TDS, 0 GH
 
So the activeness of pure water is where those hydrogen bridges are forming instead of the water molecules pulling out metallic ions to bond with? Seems a reasonable assumption.

Also seems reasonable to assume that if a highly mineralized tap water were used instead that there would be fewer of these bridges, which would have a degrading effect on the overall behavior of the solution.
It’s not the “activeness” of the water. Both are polar liquids and are miscible.

Water isn’t an “active” compound as such. Like most oxides it is very stable.
 
I think that most of this thread would disagree with "water being very stable" If you strip out the mineral ions it actively tries to replace them with whatever it is in contact with, usually that being metallic ions. Once it has those it is still a very effective solvent.
 
I think that most of this thread would disagree with "water being very stable" If you strip out the mineral ions it actively tries to replace them with whatever it is in contact with, usually that being metallic ions. Once it has those it is still a very effective solvent.
It’s because you don’t know what some of the words mean.
 
I first ran a search and didn't really find what I was looking for.
 
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