Distilled water for mixing engine coolant?

[ntsqd]

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?

 

[rszappa1]

yes

 

[eljefino]

The answer depends on where you live and the quality of your tap water, which is the presumed alternative to the distilled you mention. I suspect the makers of 50/50 premix use a quality of incoming water that has fairly generous standards, since they know the buffers in their additive package will easily cover for them.

Some places have lots of lime and scale which are actually bad for coolant systems, and need purging with citric acid.

Other places have acid rain, for which minor amounts are buffered by additives in the antifreeze already.

They brew beer with city water and, IMO, that's a finer balance of chemistry to get right. Coolant mixes just have to get in a ballpark so they don't "eat" solder, intake gaskets, or other sensitive items. And the chemistry of those items "should" allow for mediocre coolant mixes as well.

Prestone did sell a "makeup water" for a bit but I suspect not in great enough quantities to keep it on shelves.

 

[SC Maintenance]

Distilled water is just that - pure H20 (or almost so). H20 is a universal solvent, which will want to disolve other compounds. That is the point - it mixes readily with the coolant add pack without using it up.

So yes, just go buy distilled water for like $2 at the grocery store and be happy. Look for the cheapest that says "steam distilled"

@eljefino is correct, in that your tap water might be acceptable - but without a full test how would you know? I go with the grocery store stuff for as often as I need it.

 

[WeyounDS9]

As a Chemist, I can tell you that its best practices to use distilled water to top off coolant. (deionized will also do)
As long as you dont top off so much it lowers your BP, or raises your FP, too much.

Don't worry about the distilled water being "too hungry" for ions.
The mix in your coolant will bring up the ionic strength up real quick.

Never use tap water, unless stranded in the boonies, with no other possible source.

 

[oilboy123]

If I did not have a distilled water maker, I would have bought one. I use it for BPAP device, like a CPAP machine. I also just got done doing flush out on 2 cooling systems.

For those using a fair amount of distilled water. Having a distilled water maker might be worth it. I would not consider using well water where I live now. I used to live with city water with flouride, and a small a mount of chlorine that they added. I used to use that to run in cooling systems. I probably should have used distilled water.

 

[ntsqd]

I didn't intend to open up the whole "distilled vs. tap water" discussion as I'm sure that's been beaten to death.

Rather, is there something better than distilled and what is it? In mixing with the concentrated coolant does that consume some of the components of the coolant that should be doing other jobs, or are those components put in the coolant specifically to get the water to the right/best chemistry?

 

[WeyounDS9]

I didn't intend to open up the whole "distilled vs. tap water" discussion as I'm sure that's been beaten to death.

Rather, is there something better than distilled and what is it? In mixing with the concentrated coolant does that consume some of the components of the coolant that should be doing other jobs, or are those components put in the coolant specifically to get the water to the right/best chemistry?

It consumes nothing.
Its fine.
Deionized is also fine, which is a tiny step "below" distilled in terms of purity.

 

[zrxkawboy]

Prestone says to use distilled water.

 

[Jetronic]

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?

distilled water, with some oxidation inhibitors like in coolant or water wetter...

Even the example you gave uses distilled water.

Demineralized is what I use, and coolant of course.

 

[ntsqd]

The example that I gave starts with distilled and then doctors it by adding other chemicals to be a very specific chemical constituency.

That very specific chemistry might just be what would be ideal for a coolant system's water component.

It might seem like I'm looking for problems where there aren't any, but I've had a couple experiences with coolant systems in the last couple of years that have made me question whether distilled is the best choice. Systems that I know were filled with coolant and distilled that looked like local tap water had been used instead. Not to the degree of having done so, but clearly headed in that direction.

Fundamentally how does ethylene glycol and water combine? Is it a simple mixture, or is it a new compound? I had a college level general chemistry class all of about 30 years ago. I'm going to need to dredge the memory bank for the proper terms to use.

 

[WeyounDS9]

Fundamentally how does ethylene glycol and water combine? Is it a simple mixture, or is it a new compound? I had a college level general chemistry class all of about 30 years ago. I'm going to need to dredge the memory bank for the proper terms to use.

They are in solution with one another.
They do not form a new compound (molecule), the way we usually use the term.

Usually we say the ethelyne glycol is dissolved in water, but if its truly 50/50, who is to say the water is not dissolved in the etylene glycol?

They form hydrogen bridges among each other due to partial minus and plus charges on the Oxygen and the Hydrogen atoms in the molecule respectively.
This does not just apply to the water but the Ethyl. Glycol, which has those too and this is fundamentally why the BP is raised as the solution now has a stronger attraction to itself, than before.

PS: Some folks who change their engines enough to make signifcant extra power over stock, intentionelly thin out their mix to 60 or even 65% of distilled water as water has a greater heat capacity than ethylene glycol effectively enlarging their radiator w/o chaning a single part.
The risk of lowered BP is considered acceptable in this situation.
(I am a former fast and furious style street racer, from my younger/dumber days and ran aftermarket supercharged 350Zs, yes plural..)

 

[ntsqd]

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.

 

[WeyounDS9]

1) 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.

2) 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.

1) The ionic strenght of pure (ie distilled) water is lower than tap water.
Fewer ions ( charged particles).
Water, due to the electronegative nature of Oxygen, carries partial negative charges on its component atoms, but is itself not an ion.
However those partially charged sites are available for association with ions.

2) The ions in tap water would "use up" active ingredients, "additives", added to give the coolant extra properties.
(rust retarding, ph balancing via weak acid-base pairs and the like)

 

[martinq]

I've always used purified drinking water. My current setup produces water with a TDS of ~50.

 

[BHopkins]

I know that water can be over purified, to the point where it is looking for minerals to add to itself. I've seen it. But simple distilled water is not that.

Many years ago, I was managing a test lab. Among the capabilities we had were a salt fog corrosion chamber and an environmental chamber, capable of humidity up to 95%. Before I was hired to manage the lab, a supervisor from a sister lab had spec'd out a water purification system that would produce water for the corrosion chamber, and also for the humidity generators in the environmental chamber. These humidity generators were essentially brass tanks with an electric water heater element, to heat the water to the point of producing steam.

Street water was first filtered through sediment filters, then went through a water softener. Next was a pair if DI tanks in series, and lastly, the water went through an RO system.

After only a short time, I started having problems with heating elements burning out in the humidity generators of the environmental chambers. The copper sheathing of the heating elements would be eaten away, exposing the electrical element to the water in the tank, and the circuit would trip. This happened repeatedly. I had a consultant come in, and he recommended that we pull the water for the humidity generators, after the DI tanks, but before the RO system. We did this and never had another heating element burn out.

So yes, water can be too polished. But distilled water is far from there.

 

[Kira]

I refreshed a friend's cooling system as a wedding present.
Frankenbrew coolant out...rinses with clear tap water I brought...rinses with distilled water...refill using called for Dex-Cool + distilled..50:50.
RESULT: Perfect Dex 'orange-red' color.

His dad wanted to join in. We dumped his unknown, well aged coolant, rinsed with well water the locals call "liquid rock" as I used up what I had brought.
When I said it was time to go get distilled at the store, he balked and cried.
I swear he went into a "downtrodden member of the middle class" speech...most distasteful it was.
Over my objection, he used the well water.
Ugly dullness was the result.

 

[KevinMalone]

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/

 

[Rand]

if you were only using water maybe, but you are using half water half coolant.

 

[Chris142]

Once distilled water is mixed with antifreeze it will now be full of anti corrosion additives and no longer be " Hungry" for metal.

The water in my area is so full of minerals that it will plug radiators and destroy the additives of coolant quickly.