DISTILLED vs TAP WATER***WHO IS THE WINNER - PeachParts Mercedes-Benz Forum

lino · #1 10-01-2004, 01:14 PM

What's the best mix for antifreeze / coolant - Distilled Water or Tap Water?

What is Distilled Water?

Distillation is nature's way of purifying water. When the sun heats water, this causes evaporation, an example of distillation on the grand scale. Vapor rises from the surface of water, leaving behind all its impurities. These water vapors rise and cool as air temperature in the upper atmosphere drops, and the vapors change from gas to liquid, becoming water, ice or snow. If our atmosphere were not polluted, each drop of rain or snow would be pure H2O.

The production of distilled drinking water is man's attempt to copy nature's form of water purification . As with evaporation in nature, distillation actually removes water (in the form of steam vapor) from the heavier materials that are its impurities. Other types of water treatment attempt to remove contaminants from water, rather than removing water from the contaminants.

In the boiling chamber of the water distiller, tap water is heated to 212 degrees, killing bacteria and viruses. The heat produces steam, which rises, leaving behind inorganic minerals, lead, bacteria, nitrates chemicals and other contaminants in the boiling tank. As the water temperature rises, the light gases boil off and are discharged through the gaseous vent. A stainless steel condenser cools the steam, turning it into distilled water. This water passes from the condenser through an optional post carbon filter, and the purified distilled water that is 99.9 percent pure is collected in a reservoir.

Basically using tap water is bad because it could lead to corrosion of components. Some people might tell you that your tap water is as clean as the distilled you are buying. Tap water obviously varies. Apparantly, supermarket brands of distilled water vary too. The process used does not produce a particularly pure product. Can someone confirm or add to this?

mpolli · #2 10-01-2004, 02:03 PM

Back then that WAS antifreeze.

As far as the distilled water question. I need some distilled water for my battery. Last night I was emptying the tank from the dehumidifier in my basement and I thought "hmmmm, this might be close enough" This water is condensed from air moisture, and I can make lots of it!! As far as store bought, they have "Distilled" or "Purified". I think I will spend the .79 for the distilled.

Mike

Mike Murrell · #3 10-01-2004, 02:15 PM

The distilled water issue has at times become as heated as the green vs. non-green coolant argument and dino oil vs. syn. oil.

A tech named Stu Ritter on the Ritter-Easley MB forums says NOT to use distilled water in MBs.

I asked this same question a few yrs. back. The thread is below.

Using Distilled water in Coolant

Duke2.6 · #4 10-01-2004, 04:20 PM

This debate is fueled primarily by misconceptions.

Way back in the fifties, if not before, some thought that running pure distilled water in a cooling systems was good, but without corrosion inhibitors, distilled water will rapidly corrode the system. Once the word got out, somehow this advice got turned into "don't use distilled water with antifreeze", which is wrong!

Ethylene glycol is carefully blended with various chemicals (both organic and inorganic in the case of HOAT anti-freeze that DC recommends) to prevent cooling system corrosion. Once you mix distilled water with antifreeze the original balance of various chemicals is preserved as intended by the manufacturer, and most commercial antifreeze products are blended to provide ideal corrosion protection when mixed with an equal quantity of pure water.

Using tap water can introduce additional chemicals to the solution, some of which can be detrimental. Chlorine, in particular, which is added to most domestic water can form hydrochloric acid, which is corrosive, and calcium can preciptate out and form cooling system deposits.

Most OEs say that clean, potable water is okay to mix with antifreeze, but there is a lot mineral and other ion content variation in "clean, potable water", so distilled water is a better choice since it contains lower concentrations of undesireable ions than even the "cleanest" tap water and is least likely to upset the intended chemical balance when used to dilute antifreeze.

Bottom line: Most tap water is "okay" (unless it is clear from smell or taste that it has high mineral or chlorine content), but distilled water is BEST!

Duke

mpolli · #5 10-01-2004, 05:00 PM

It seems to me getting water without chlorine in it would be reason enough to use distilled water.

In the thread shown in post 4 of this thread, someone made the comment:

"Finally, if you use MB Coolant, you will have that little tell-tale chemical which will pinpoint any leaks."

Is there any truth to this? What are they talking about?

Thanks,

Mike

MikeTangas · #6 10-01-2004, 06:26 PM

Minor coolant leaks you cannot see drip, will leave a telltale "crust". It seems to be more pronounced with the MB coolant.

Hatterasguy · #7 10-01-2004, 06:42 PM

I think distilled water is overkill, I'm sure my SDL has never seen a drop of it and the cooling system is still clean. My radiator died from old age, it still cooled fine. Unless you live in an area with a lot of crap in the water, like lime in FL for example tap water is fine. Tap water these days is filtered really well.

mpolli · #8 10-01-2004, 07:04 PM

It died from old age? Not corrosion?

Mike

blackmercedes · #9 10-01-2004, 07:31 PM

Quote:

Originally Posted by Duke2.6

Way back in the fifties, if not before, some thought that running pure distilled water in a cooling systems was good, but without corrosion inhibitors, distilled water will rapidly corrode the system. Once the word got out, somehow this advice got turned into "don't use distilled water with antifreeze", which is wrong!

That is right. In fact, running tap water alone in your cooling system will also cause it to corrode. The mixture of the coolant and the water provides the balance of lowering the freezing point, raising the boiling point, and inhibiting corrosion.

Most makes now recommend distilled water, and why not? It's cheap and plentiful.

Duke2.6 · #10 10-01-2004, 08:26 PM

Quote:

Originally Posted by MikeTangas

Minor coolant leaks you cannot see drip, will leave a telltale "crust". It seems to be more pronounced with the MB coolant.

Since HOAT and IAT blends have some inorganic material they will leave a "trail" at any leak. I can tell you from experience that Dexcool, which has NO inorganic material leaves no trail other than maybe a slight hint of the orange die.

It's also my opinion from experience that Dexcool has more tendecy to seep from hose connections and other potential leak sources. The inorganics in HOAT and IAC precipitate out and form deposits at the leak sources, and these deposits may actually plug the leak path.

Duke

lino · #11 10-01-2004, 09:55 PM

Just found this:

...Coolant is a 50-50 mixture of purified (not tap and not distilled) water and antifreeze/coolant. Do not add straight water if the reservoir is completely empty as this can cause your car to overheat.

Source:
http://www.***************/mercedes-auto-parts/mercedes-auto-maintenance.html

Duke2.6 · #12 10-01-2004, 10:45 PM

Some antifreeze products are sold "premixed" with water, so they are the equivalent of mixing equal parts parts of full strength antifreeze and water. Antifreeze is antifreeze, water is water, and a 50/50 mixture of the two is called "coolant" since a 50/50 mix of full strength antifreeze and water is what most OEs call "coolant".

These products are "convenient" because they require no mixing, but they are rather expensive and it is not that hard to add equal amounts of full strength antifreeze and distilled water when doing a coolant change. Unless there is a leak of a faulty pressure cap, it is unusual for the coolant level to drop between three year changes, unless the car is driven more than 30K miles.

If you start with a 50/50 mix and at some point the reservoir is a bit low and needs a few ounces, using either distilled water or straight antifreeze will not have a major impact on the desired 50/50 mix, which is the optimum tradeoff between corrosion inhibition and thermal capacity.

Duke

Hatterasguy · #13 10-02-2004, 11:38 PM

Quote:

Originally Posted by mpolli

It died from old age? Not corrosion?

Mike

The plastic around the crimp started to crack, the radaitor was fine other then that.

W140 S600 · #14 10-03-2004, 01:04 PM

Quote:

Originally Posted by Hatterasguy

The plastic around the crimp started to crack, the radaitor was fine other then that.

Well actually Chris, it was murdered by a flathead screwdriver...oh and various other instruments "testing" the quality of the 16+ year old radiator

#15 10-03-2004, 02:28 PM

Engine coolant and engine oil type, and interval to change them seem to generate the most opinions on this and other auto forums. With or without valid engineering reasons is another topic. I spoke to friends of mine who are on the forefront of engine testing:
Their advise to me:
1.) AL alloy engine/radiator and plastic top tank is a different animal from gray iron engine.. Treat it with respect else you will pay (dearly).

2.) Use the manufacturer premix 50/50 engine coolant.

3.) if you have to mix your own, use distilled water and NOT TAP WATER

4.) Distilled water is only $2-$3 cost vs tapwater, Very cheap insurance policy.

4.) Change coolant per maufacturers' recommendations.

My advise:
perferred method: Use MB 50/50 premix (its only $10-$20/gal)
alternative: Zerex-G05 ($8/gal) +distilled water ($0.70/gal) mixed to 50/50 by volume.

Dont use Dexcool on a MB Al engine.