Distilled versus tap water

[mjoekingz28]

What was GM thinking when they started recommending "clean, drinkable" water 50/50 with Dex-Cool?


Is it preferred or did they give in since they figured some owners wouldnt use distilled anyway?


I doubt we will ever see a difference between the two (guess like a syn vs conv debate...or the like) but which is better: drinkable tap or distilled from a jug?

 

[19jacobob93]

I don't like drinking tap water nor do I put it in my car! I would drink mineral water but I also wouldn't put that in my car...
Distilled/demineralized water all the way when it comes to cooling systems, it's dirt cheap too so why not

 

[Greasymechtech]

Always use distilled, deionized, or reverse osmosis water. Save the tap water for emergencies.

I don't want or need any crud minerals from my well or city water mixed in with my coolant, especially with the long service life of newer coolants.

 

[zach1900]

I've heard that distilled water is actually worse for your cooling system, missing unstable ions always causing hotspots, I forget the exact mechanism, I'll try to find the article.

 

[zach1900]

Distilled is better why?

 

[zrxkawboy]

Originally Posted By: zach1900
Distilled is better why?


No minerals to leave deposits in your cooling system.

 

[Oil Changer]

It really doesn't matter. If you want the "best" use distilled.

 

[Oil Changer]

Good. I want to read that.

Originally Posted By: zach1900
I've heard that distilled water is actually worse for your cooling system, missing unstable ions always causing hotspots, I forget the exact mechanism, I'll try to find the article.

 

[DBMaster]

I have used distilled or R/O (I have an R/O system at home) since the late 80's. Prior to that, I had a 72 Pontiac that only saw tap water. The radiator in it lasted just as long as in the 1989 Honda and I never noticed any extra buildup when I accesses parts like the water pump or thermostat and hoses.

So, even though I do use the purified water I'm not 100% convinced that it makes much difference. Current coolants do a better job of keeping corrosion at bay than those of thirty years ago. Plus, with far less frequent coolant changes (at least in my case) there's not a whole lot of water in the system.

pH level may be an issue if you have acidic tap water, but then again, that's another thing that coolant buffers.

 

[OneEyeJack]

Some areas have tap water that is really junked up with a lot of minerals and other stuff and is often characterized as "hard water".

For me, I'd use distilled water because it's probably has less stuff in it than tap water. The tap water where I live is called hard water and caused problems with plumbing. I don't want that water in my radiator.

 

[double vanos]

FWIW my wifes' iron uses only clean drinking water - no distilled water, for whatever reason. This came from the manual , which when I read it flabbergasted me. Why in the heck would you want water that isn't 100% pure in the steam passages of your iron? Well, it seems the manufacturer has some reason, but I can't figure it out...

 

[spackard]

I think with the clothes irons you'll risk a flash-boil with pure water. Though nothing in the manuals will tell you that.

 

[SHOZ]

Originally Posted By: zach1900
I've heard that distilled water is actually worse for your cooling system, missing unstable ions always causing hotspots, I forget the exact mechanism, I'll try to find the article.


That is probably true using straight water. Once it's mixed with AF there are plenty of ions to go around.

 

[Falken]

I don't mix usually, but when I do, I use distilled.

When I was in school that was one of the first projects many people liked to get out of the way was change the coolant in their old beater.

And, we all brought in jugs of distilled water. Lots of minerals in tap water, don't use it.

 

[Kestas]

Originally Posted By: zach1900
I've heard that distilled water is actually worse for your cooling system, missing unstable ions always causing hotspots, I forget the exact mechanism, I'll try to find the article.

You're thinking of deionized water. It tries to strip metal from its base surface. But this phenomenon goes away the minute you splash antifreeze or dirty water into it. Use distilled or deionized water in your cooling system with confidence. I do.

We have deionized water on tap at work. I use it in all our coolant systems that produce swarf.

Don't use rain water. It has too much carboxylic acid in it.

 

[Claud]

The groundwater in my area is very "hard", that is there is a lot of calcium carbonate in it from the chalk substrate. The same stuff that furs up heater elements and hot water pipes. However I have used tap water for many years with no discernable ill effects on hundreds of vehicles. I always use a 50/50 antifreeze mix, nothing else, no water wetter or other proprietary additives.

Incidentally in several double blind independent tests tap water from where I live, and central London where it might have been recycled a number of times, has come out much more pure and better to drink than any bottled water from supermarkets.

Claud.

 

[Chris142]

Originally Posted By: zach1900
I've heard that distilled water is actually worse for your cooling system, missing unstable ions always causing hotspots, I forget the exact mechanism, I'll try to find the article.
once its mixed with coolant its no longer clean distilled water.

 

[4wheeldog]

Originally Posted By: Kestas
Originally Posted By: zach1900
I've heard that distilled water is actually worse for your cooling system, missing unstable ions always causing hotspots, I forget the exact mechanism, I'll try to find the article.

You're thinking of deionized water. It tries to strip metal from its base surface. But this phenomenon goes away the minute you splash antifreeze or dirty water into it. Use distilled or deionized water in your cooling system with confidence. I do.

We have deionized water on tap at work. I use it in all our coolant systems that produce swarf.

Don't use rain water. It has too much carboxylic acid in it.


What he said.....
I went to a boiler class years ago. The guy giving the class explained why deionized water was bad in boilers. He called it "Hungry water". He then tried to make the case that the same was true in your car's cooling system.

I waited until lunch to quiz him on this, and after lunch he amended his statement that, if you were not using antifreeze, deionized or distilled water were poor choices. With the use of 50% antifreeze, "Hungry water" has its needs satiated.

 

[Leo99]

I use distilled water, too, but it sounds like it might be another car myth that it's better than tap water to mix in with coolant.

 

[Cressida]

Originally Posted By: Kestas

Don't use rain water. It has too much carboxylic acid in it.


I have been using rain water. Can you explain more about the carboxylic acid and how it gets into rain water? This is something I've not heard of before so want to learn more.

Regarding tap water, some cities are adding some type of mineral to the water supply so that it helps to seal smaller leaks in their system water lines. This forms a crusty film on water pipes and inside of toilets and is something I would avoid using as a coolant.