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

lino · #1 10-01-2004, 02:14 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, 03:03 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, 03:15 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.

http://www.peachparts.com/shopforum/showthread.php?t=6923&highlight=distilled

Duke2.6 · #4 10-01-2004, 05:20 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, 06:00 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, 07:26 PM

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

blackmercedes · #7 10-01-2004, 08:31 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.

#8 10-03-2004, 03:28 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.

lino · #9 10-03-2004, 06:12 PM

So are you saying that Mercedes offers a mixed and unmixed antifreeze?

Hatterasguy · #10 10-03-2004, 08:44 PM

MB doesn't offer a premix. If they did I'd buy it.

SteveM · #11 05-12-2009, 01:40 PM

Recently, the radiator/coolant icon on the dash of my 1986, 560SL lights up intermittently. However, the guage does not indicate that the car is running hot. I noticed that the coolant in the overflow reservoir is about an inch below the point where the reservoir is molded together. Could this be causing the icon on the dash to come on?

Steve M
1986 560SL
90K

G-Benz · #12 05-12-2009, 02:01 PM

Quote:

Originally Posted by SteveM

Recently, the radiator/coolant icon on the dash of my 1986, 560SL lights up intermittently. However, the guage does not indicate that the car is running hot. I noticed that the coolant in the overflow reservoir is about an inch below the point where the reservoir is molded together. Could this be causing the icon on the dash to come on?

Steve M
1986 560SL
90K

The "low coolant" light is triggered whenever the coolant level in the reservoir is considered low and needs to be topped off. Not an overheat issue as there is still plenty of coolant available to circulate through the engine. It just gives you fair warning to address the issue before you run out completely and cause real permanent damage.

If you top off with coolant/tap water/distilled water/Kool Aid, etc. whatever, the light should no longer be illuminated. If it is still illuminated, then the corrosion on the coolant sensor terminals are causing a "false positive", in which case you need to replace the sensor (located near the bottom of the coolant reservoir).

Back on topic:

My indie say "distilled water only!" but from experience, I find that the issue is really about regular maintenance, not chemicals. Although there are recommended coolant products for MB, the issue about water really is about the duration of said mixture circulating through the engine before it is refreshed.

Same with the "dino vs. synth" argument. If you are changing oil at regular intervals (7500 mi), it should not matter what oil you are using.

For either case, it you are going along with no regard for routine maintenance using the same recirculated oil and coolant, there is no doubt you are going to destroy something eventually, regardless of the "snake oil" properties of the product(s) being used...

Randy · #13 05-12-2009, 04:06 PM

We buy premixed coolant by the semi-trailer load for industrial engines: it's glycol and deionized water, mostly because at some locations the water is of poor quality, full of iron, etc., but also because we can be certain the corrosion inhibitors are there and the freeze point is correct for the location. We use enough glycol to get appropriate freeze protection, but no more, as the cooling capacity of the systems is reduced as the glycol concentration increases (but the boiling point in a pressurized system increases, I know; these aren't pressurized as cars' are).
I opened my Benz up after 20+ years of somewhat indifferent care by the PO and found... nothing wrong in the cooling system. It had probably had the same green stuff in it for 5 or more years. Our tap water is fairly soft and doesn't cause problems. I have a car I've owned since 1974 and no problems ever with the cooling system, with just general good maintenance, nothing elaborate. If your tap water does not ruin the coffee maker, sinks, toilets, or water heater, you probably won't have any problem with it as long as you use the right coolant and change it every so often; if it does, don't use it in your cooling system.
Don't spend all your time worrying about your car; spend most of your time enjoying it.

#14 10-03-2004, 10:35 PM

First of all some definitions.
The term purified water refers to water which has been produced by distillation, deionization or reverse osmosis. Simply stated any of the three methods can produce water of the same chemical purity for practical purposes.

I would say that if the choice was given to make a few gallpns of a 50 percent solution of antifreeze the 80 cents or so that a gallon of purified water would cost would be immaterial.

Finally you would not be adding iron, chlorine or any other substances in tap water to your brand new antifreeze solution.

Purified water has a known purity, tap water is all over the place depending on the location and even he time of the year. In the northeast, after the snow melts, lots of salt runs into the rivers that provide our water.

That's why I make my coffee with purified water or spring water, it just tastes better and is crystal clear.

lino · #15 10-04-2004, 12:00 PM

Distilled Water is the Winner for me.

Thank you everyone for participating in this thread and for all the educational information you provided. I really appreciate it. I used to use tap water as a mix, not knowing any better...never again.