I have inadvertently added a little tap water into my coolant reservoir. Car is running fine. Do I need to worry about anything now, or do I need to bleed the system just yet? Thanks

Water is what you mix with coolant to make a 50/50 mix of anti-freeze and water. Usually distilled water but a small amount of tap water will do no harm. No you don’t have to bleed the system.

Thanks. It’s my first car so was not sure.

About a 100ml at most. But not sure it’s up to

That is very little. If you have to add coolant regularly you may have a leak. It doesn’t appear you do. Just check your levels Every couple of weeks. You could get a coolant tester. They’re cheap to test antifreeze concentration. Then look up the maintenance schedule and change coolant when it’s du…

In more than 60 years of driving I have never mixed my coolant with anything but tap water. I suppose it could depend on where you live. Our water is not very "hard, nobody I know uses a water softener. My water comes from the Niagara river.

I would not do anything right now to the cooling system. 100ml of tap water isn’t going to harm anything, but I would not make a practice of using tap water. Eventually you could get enough minerals to do some damage. I suggest that you get a gallon of premix for your vehicle. Most “universal” c…

and bleed the air out of the system.

Best to use distilled I guess but for 50 years I just used tap water and never had a problem.

Engine Coolant mixed with tap water

General Discussion

George_San_Jose1 July 27, 2021, 11:09pm 7

100 ml added to the overflow tank shouldn’t cause problems. However, before freezing temperatures arrive, make sure to have the coolant tested for proper freeze protection.

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Engine Coolant mixed with tap water

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